--- a/catalyst-3.0_rc1/catalyst/defaults.py	
+++ a/catalyst-3.0_rc1/catalyst/defaults.py	
@@ -39,6 +39,7 @@ confdefaults={
 	"PythonDir": "./catalyst",
 	"repo_basedir": "/usr",
 	"repo_name": "portage",
+	"sed": "sed",
 	"sharedir": "/usr/share/catalyst",
 	"shdir": "/usr/share/catalyst/targets/",
 	"snapshot_cache": "/var/tmp/catalyst/snapshot_cache",
--- a/catalyst-3.0_rc1/catalyst/main.py	
+++ a/catalyst-3.0_rc1/catalyst/main.py	
@@ -343,6 +343,12 @@ def _main(parser, opts):
 	conf_values['compress_definitions'] = COMPRESS_DEFINITIONS
 	# TODO add capability to config/spec new definitions
 
+	# detect GNU sed
+	for sed in ('/usr/bin/gsed', '/bin/sed', '/usr/bin/sed'):
+		if os.path.exists(sed):
+			conf_values["sed"] = sed
+			break
+
 	# Start checking that digests are valid now that hash_map is initialized
 	if "digests" in conf_values:
 		digests = set(conf_values['digests'].split())
--- a/catalyst-3.0_rc1/targets/stage1/stage1-chroot.sh	
+++ a/catalyst-3.0_rc1/targets/stage1/stage1-chroot.sh	
@@ -49,7 +49,7 @@ make_destpath /tmp/stage1root
 # First, we drop in a known-good baselayout
 [ -e ${clst_make_conf} ] && echo "USE=\"${USE} -build\"" >> ${clst_make_conf}
 run_merge "--oneshot --nodeps sys-apps/baselayout"
-sed -i "/USE=\"${USE} -build\"/d" ${clst_make_conf}
+${clst_sed} -i "/USE=\"${USE} -build\"/d" ${clst_make_conf}
 
 # Now, we install our packages
 if [ -e ${clst_make_conf} ]; then
@@ -62,10 +62,10 @@ if [ -e ${clst_make_conf} ]; then
 fi
 
 run_merge "--oneshot ${clst_buildpkgs}"
-sed -i "/USE=\"-* build ${BOOTSTRAP_USE} ${clst_HOSTUSE}\"/d" \
+${clst_sed} -i "/USE=\"-* build ${BOOTSTRAP_USE} ${clst_HOSTUSE}\"/d" \
 	${clst_make_conf}
 for useexpand in ${clst_HOSTUSEEXPAND}; do
 	x="clst_${useexpand}"
-	sed -i "/${useexpand}=\"${!x}\"/d" \
+	${clst_sed} -i "/${useexpand}=\"${!x}\"/d" \
 	${clst_make_conf}
 done
--- a/catalyst-3.0_rc1/targets/stage2/stage2-chroot.sh	
+++ a/catalyst-3.0_rc1/targets/stage2/stage2-chroot.sh	
@@ -21,5 +21,5 @@ fi
 ${clst_repo_basedir}/${clst_repo_name}/scripts/bootstrap.sh ${bootstrap_opts} || exit 1
 
 # Clean-up USE again
-sed -i "/USE=\"\${USE} bindist\"/d" "${clst_make_conf}"
-sed -i "/USE=\"bindist\"/d" "${clst_make_conf}"
+${clst_sed} -i "/USE=\"\${USE} bindist\"/d" "${clst_make_conf}"
+${clst_sed} -i "/USE=\"bindist\"/d" "${clst_make_conf}"
--- a/catalyst-3.0_rc1/targets/support/bootloader-setup.sh	
+++ a/catalyst-3.0_rc1/targets/support/bootloader-setup.sh	
@@ -79,7 +79,7 @@ case ${clst_hostarch} in
 		echo "message=/boot/boot.msg" >> ${icfg}
 
 		# Here is where I fix up the boot.msg file.
-		sed -e 's/ARCH/PowerPC/' \
+		${clst_sed} -e 's/ARCH/PowerPC/' \
 			-e 's/HARDWARE/Apple and IBM hardware/' \
 			-i $kmsg
 
--- a/catalyst-3.0_rc1/targets/support/chroot-functions.sh	
+++ a/catalyst-3.0_rc1/targets/support/chroot-functions.sh	
@@ -87,7 +87,7 @@ setup_myfeatures(){
 		else
 			clst_root_path=/ run_merge --oneshot --noreplace sys-devel/distcc || exit 1
 		fi
-		sed -i '/USE="${USE} -avahi -gtk -gnome"/d' ${clst_make_conf}
+		${clst_sed} -i '/USE="${USE} -avahi -gtk -gnome"/d' ${clst_make_conf}
 		mkdir -p /etc/distcc
 		echo "${clst_distcc_hosts}" > /etc/distcc/hosts
 
@@ -186,7 +186,7 @@ setup_pkgmgr(){
 		echo "Adding USE=\"\${USE} $1\" to make.conf for portage build"
 		[ -e "${clst_make_conf}" ] && echo "USE=\"\${USE} $1\"" >> "${clst_make_conf}"
 		run_merge --oneshot --update --newuse sys-apps/portage
-		sed -i "/USE=\"\${USE} $1\"/d" "${clst_make_conf}"
+		${clst_sed} -i "/USE=\"\${USE} $1\"/d" "${clst_make_conf}"
 	else
 		run_merge --oneshot --update --newuse sys-apps/portage
 	fi
@@ -241,8 +241,8 @@ cleanup_stages() {
 
 	# Remove bindist from use
 	# this is handled independantly in stage2, changes here should be mirrored there
-	sed -i "/USE=\"\${USE} bindist\"/d" "${clst_make_conf}"
-	sed -i "/USE=\"bindist\"/d" "${clst_make_conf}"
+	${clst_sed} -i "/USE=\"\${USE} bindist\"/d" "${clst_make_conf}"
+	${clst_sed} -i "/USE=\"bindist\"/d" "${clst_make_conf}"
 
 	[ "${clst_target}" != "tinderbox" ] && rm -f /var/log/emerge.log /var/log/portage/elog/*
 }
@@ -260,7 +260,7 @@ die() {
 
 make_destpath() {
 	# ROOT is / by default, so remove any ROOT= settings from make.conf
-	sed -i '/ROOT=/d' ${clst_make_conf}
+	${clst_sed} -i '/ROOT=/d' ${clst_make_conf}
 	export ROOT=/
 	if [ "${1}" != "/" -a -n "${1}" ]
 	then
--- a/catalyst-3.0_rc1/targets/support/create-iso.sh	
+++ a/catalyst-3.0_rc1/targets/support/create-iso.sh	
@@ -87,7 +87,7 @@ fi
 isoroot_checksum() {
 	echo "Creating checksums for all files included in the iso, please wait..."
 	find "${clst_target_path}" -type f ! -name 'isoroot_checksums' ! -name 'isolinux.bin' -exec sha512sum {} + > "${clst_target_path}"/isoroot_checksums
-	sed -i "s#${clst_target_path}##" "${clst_target_path}"/isoroot_checksums
+	${clst_sed} -i "s#${clst_target_path}##" "${clst_target_path}"/isoroot_checksums
 }
 
 run_mkisofs() {
@@ -203,10 +203,10 @@ case ${clst_hostarch} in
 		if [ -f "${clst_target_path}/ppc/bootinfo.txt" ]
 		then
 			echo "bootinfo.txt found .. updating it"
-			sed -i -e \
+			${clst_sed} -i -e \
 			's#^<description>.*</description>$#<description>'"${clst_iso_volume_id}"'</description>#' \
 			"${clst_target_path}/ppc/bootinfo.txt"
-			sed -i -e \
+			${clst_sed} -i -e \
 			's#^<os-name>.*</os-name>$#<os-name>'"${clst_iso_volume_id}"'</os-name>#' \
 			"${clst_target_path}/ppc/bootinfo.txt"
 		fi
--- a/catalyst-3.0_rc1/targets/support/kmerge.sh	
+++ a/catalyst-3.0_rc1/targets/support/kmerge.sh	
@@ -245,7 +245,7 @@ then
 		if [ ! "${clst_kextraversion}" = "" ]
 		then
 			echo "Setting extraversion to ${clst_kextraversion}"
-			sed -i -e "s:EXTRAVERSION \(=.*\):EXTRAVERSION \1-${clst_kextraversion}:" /usr/src/linux/Makefile
+			${clst_sed} -i -e "s:EXTRAVERSION \(=.*\):EXTRAVERSION \1-${clst_kextraversion}:" /usr/src/linux/Makefile
 			echo ${clst_kextraversion} > /tmp/kerncache/${clst_kname}/${clst_kname}-${clst_version_stamp}.EXTRAVERSION
 		else
 			touch /tmp/kerncache/${clst_kname}/${clst_kname}-${clst_version_stamp}.EXTRAVERSION
@@ -262,7 +262,7 @@ $(portageq contents / $(portageq best_visible / "${clst_ksource}" 2>/dev/null) 2
 	if [ ! "${clst_kextraversion}" = "" ]
 	then
 		echo "Setting extraversion to ${clst_kextraversion}"
-		sed -i -e "s:EXTRAVERSION \(=.*\):EXTRAVERSION \1-${clst_kextraversion}:" /usr/src/linux/Makefile
+		${clst_sed} -i -e "s:EXTRAVERSION \(=.*\):EXTRAVERSION \1-${clst_kextraversion}:" /usr/src/linux/Makefile
 	fi
 fi
 
@@ -275,12 +275,12 @@ make_destpath
 
 
 build_kernel
-sed -i "/USE=\"\${USE} ${clst_kernel_use} \"/d" ${clst_make_conf}
+${clst_sed} -i "/USE=\"\${USE} ${clst_kernel_use} \"/d" ${clst_make_conf}
 # grep out the kernel version so that we can do our modules magic
 VER=`grep ^VERSION\ \= /usr/src/linux/Makefile | awk '{ print $3 };'`
 PAT=`grep ^PATCHLEVEL\ \= /usr/src/linux/Makefile | awk '{ print $3 };'`
 SUB=`grep ^SUBLEVEL\ \= /usr/src/linux/Makefile | awk '{ print $3 };'`
-EXV=`grep ^EXTRAVERSION\ \= /usr/src/linux/Makefile | sed -e "s/EXTRAVERSION =//" -e "s/ //g"`
+EXV=`grep ^EXTRAVERSION\ \= /usr/src/linux/Makefile | ${clst_sed} -e "s/EXTRAVERSION =//" -e "s/ //g"`
 clst_fudgeuname=${VER}.${PAT}.${SUB}${EXV}
 
 unset USE
--- a/catalyst-3.0_rc1/targets/support/livecdfs-update.sh	
+++ a/catalyst-3.0_rc1/targets/support/livecdfs-update.sh	
@@ -7,7 +7,7 @@ source /tmp/chroot-functions.sh
 # Allow root logins to our CD by default
 if [ -e /etc/ssh/sshd_config ]
 then
-	sed -i 's:^#PermitRootLogin\ yes:PermitRootLogin\ yes:' \
+	${clst_sed} -i 's:^#PermitRootLogin\ yes:PermitRootLogin\ yes:' \
 		/etc/ssh/sshd_config
 fi
 
@@ -73,7 +73,7 @@ fi
 # Setup sudoers
 if [ -f /etc/sudoers ]
 then
-	sed -i '/NOPASSWD: ALL/ s/^# //' /etc/sudoers
+	${clst_sed} -i '/NOPASSWD: ALL/ s/^# //' /etc/sudoers
 fi
 
 # Setup links for ethernet devices
@@ -113,7 +113,7 @@ echo "####################################################" >> ${clst_make_conf}
 cat ${clst_make_conf}.old >> ${clst_make_conf}
 
 # devfs tweaks
-[ -e /etc/devfsd.conf ] && sed -i '/dev-state/ s:^:#:' /etc/devfsd.conf
+[ -e /etc/devfsd.conf ] && ${clst_sed} -i '/dev-state/ s:^:#:' /etc/devfsd.conf
 
 # Add some helpful aliases
 echo "alias cp='cp -i'" >> /etc/profile
@@ -153,10 +153,10 @@ fi
 # Setup configured display manager
 if [ -n "${clst_livecd_xdm}" ]
 then
-	sed -i \
+	${clst_sed} -i \
 		-e "s:^#\\?DISPLAYMANAGER=.\+$:DISPLAYMANAGER=\"${clst_livecd_xdm}\":" \
 		/etc/rc.conf
-	sed -i \
+	${clst_sed} -i \
 		-e "s:^#\\?DISPLAYMANAGER=.\+$:DISPLAYMANAGER=\"${clst_livecd_xdm}\":" \
 		/etc/conf.d/xdm
 fi
@@ -175,21 +175,21 @@ case ${clst_livecd_type} in
 	gentoo-release-universal)
 		cat /etc/generic.motd.txt /etc/universal.motd.txt \
 			/etc/minimal.motd.txt > /etc/motd
-		sed -i 's:^##GREETING:Welcome to the Gentoo Linux Universal Installation CD!:' /etc/motd
+		${clst_sed} -i 's:^##GREETING:Welcome to the Gentoo Linux Universal Installation CD!:' /etc/motd
 	;;
 	gentoo-release-minimal)
 		cat /etc/generic.motd.txt /etc/minimal.motd.txt > /etc/motd
-		sed -i 's:^##GREETING:Welcome to the Gentoo Linux Minimal Installation CD!:' /etc/motd
+		${clst_sed} -i 's:^##GREETING:Welcome to the Gentoo Linux Minimal Installation CD!:' /etc/motd
 	;;
 	gentoo-release-live*)
 		cat /etc/generic.motd.txt \
 			/etc/minimal.motd.txt /etc/livecd.motd.txt > /etc/motd
-		sed -i -e 's:^##GREETING:Welcome to the Gentoo Linux LiveCD!:' \
+		${clst_sed} -i -e 's:^##GREETING:Welcome to the Gentoo Linux LiveCD!:' \
 			-e "s:##DISPLAY_MANAGER:${clst_livecd_xdm}:" /etc/motd
 	;;
 	gentoo-gamecd)
 		cat /etc/generic.motd.txt /etc/gamecd.motd.txt > /etc/motd
-		sed -i 's:^##GREETING:Welcome to the Gentoo Linux ##GAME_NAME GameCD!:' /etc/motd
+		${clst_sed} -i 's:^##GREETING:Welcome to the Gentoo Linux ##GAME_NAME GameCD!:' /etc/motd
 	;;
 esac
 
@@ -200,7 +200,7 @@ if [ -n "${clst_livecd_splash_theme}" ]
 then
 	if [ -d /etc/splash/${clst_livecd_splash_theme} ]
 	then
-		sed -i \
+		${clst_sed} -i \
 			-e "s:# SPLASH_THEME=\"gentoo\":SPLASH_THEME=\"${clst_livecd_splash_theme}\":" \
 			-e "/^# SPLASH_TTYS=/ s/^#//" \
 			/etc/conf.d/splash
@@ -229,7 +229,7 @@ case ${clst_livecd_type} in
 			rm /tmp/gamecd.conf
 
 			# Here we replace out game information into several files
-			sed -i -e "s:##GAME_NAME:${GAME_NAME}:" /etc/motd
+			${clst_sed} -i -e "s:##GAME_NAME:${GAME_NAME}:" /etc/motd
 
 			# Here we setup our xinitrc
 			echo "exec ${GAME_EXECUTABLE}" > /etc/X11/xinit/xinitrc
@@ -276,7 +276,7 @@ case ${clst_livecd_type} in
 					/etc/X11/gdm/custom.conf
 			else
 				cp -f /etc/X11/gdm/gdm.conf /etc/X11/gdm/gdm.conf.old
-				sed -i \
+				${clst_sed} -i \
 					-e 's:TimedLoginEnable=false:TimedLoginEnable=true:' \
 					-e 's:TimedLoginDelay=30:TimedLoginDelay=10:' \
 					-e 's:AllowRemoteRoot=true:AllowRemoteRoot=false:' \
@@ -286,7 +286,7 @@ case ${clst_livecd_type} in
 
 				if [ -n "${clst_livecd_users}" ] && [ -n "${first_user}" ]
 				then
-					sed -i \
+					${clst_sed} -i \
 						-e "s:TimedLogin=:TimedLogin=${first_user}:" \
 						/etc/X11/gdm/gdm.conf
 				fi
@@ -296,7 +296,7 @@ case ${clst_livecd_type} in
 		# This gives us our list of system packages for the installer
 		mkdir -p /usr/livecd
 		### XXX: Andrew says we don't need this anymore
-		USE="-* $(cat /var/db/pkg/sys-libs/glibc*/USE)" emerge -eqp @system | grep -e '^\[ebuild' | sed -e 's:^\[ebuild .\+\] ::' -e 's: .\+$::' > /usr/livecd/systempkgs.txt
+		USE="-* $(cat /var/db/pkg/sys-libs/glibc*/USE)" emerge -eqp @system | grep -e '^\[ebuild' | ${clst_sed} -e 's:^\[ebuild .\+\] ::' -e 's: .\+$::' > /usr/livecd/systempkgs.txt
 
 		# This is my hack to reduce tmpfs usage
 		cp -r ${clst_repo_basedir}/${clst_repo_name}/profiles /usr/livecd
@@ -331,10 +331,10 @@ case ${clst_livecd_type} in
 						/home/${username}/Desktop
 					cp -f /usr/share/applications/installer-dialog.desktop \
 						/home/${username}/Desktop
-					sed -i -e \
+					${clst_sed} -i -e \
 						's:Exec=installer-dialog:Exec=sudo installer-dialog:' \
 						/home/${username}/Desktop/installer-dialog.desktop
-					sed -i -e 's:Exec=installer-gtk:Exec=installer:' \
+					${clst_sed} -i -e 's:Exec=installer-gtk:Exec=installer:' \
 						/home/${username}/Desktop/installer-gtk.desktop
 				fi
 				chown -R ${username}:100 /home/${username}
@@ -369,12 +369,12 @@ esac
 # We want the first user to be used when auto-starting X
 if [ -e /etc/startx ]
 then
-	sed -i "s:##STARTX:echo startx | su - '${first_user}':" /root/.bashrc
+	${clst_sed} -i "s:##STARTX:echo startx | su - '${first_user}':" /root/.bashrc
 fi
 
 if [ -e /lib/rcscripts/addons/udev-start.sh ]
 then
-	sed -i "s:\t\[\[ -x /sbin/evms_activate:\t\[\[ -x \${CDBOOT} \]\] \&\& \[\[ -x /sbin/evms_activate:" /lib/rcscripts/addons/udev-start.sh
+	${clst_sed} -i "s:\t\[\[ -x /sbin/evms_activate:\t\[\[ -x \${CDBOOT} \]\] \&\& \[\[ -x /sbin/evms_activate:" /lib/rcscripts/addons/udev-start.sh
 fi
 
 env-update