After finishing stage 3, you're told how to use the GRP packages (section 15. Using GRP) if you prefer to not wait for the big stuff (xfree, gnome, kde) to compile. But, at that point, you're inside the chroot, and can't access the cd. The instructions should have the installer first mount their live cd inside the chroot environment: mount -t iso9660 /dev/hdX /mnt/cdrom and then cd to the packages directory: cd /mnt/cdrom/gentoo/packages before attempting to run the script, grp-install.sh.
<pre caption="Getting ready for GRP"> # <c>mkdir /mnt/gentoo/GRP</c> # <c>mount -o bind /mnt/cdrom/gentoo/packages /mnt/gentoo/GRP</c> </pre> This is already mentioned/taken care of with these lines earlier on in the doc. Cheers, //zhen