This adds 32-bit little endian MIPS support to the v8-9999 ebuild.
Big endian and 64bit aren't mentioned in the v8 sources so I chose
to let the ebuild bail out early if one tries to build it on 64bit
and/or big endian MIPS machines.

Very lightly tested, but the resulting v8 works so far on my
mipsel-softfloat-linux-gnu machines.

--- v8-9999.ebuild~mips	2013-04-29 21:01:08.000000000 +0200
+++ v8-9999.ebuild	2013-07-09 13:02:26.002025657 +0200
@@ -66,6 +66,28 @@ src_configure() {
 				myconf+=" -Darmv7=0"
 			fi
 			myconf+=" $(gyp_use neon arm_neon)" ;;
+		mips*)
+			if [[ ${CHOST} == mips*el* ]] ; then
+				myarch="mipsel"
+				myconf+=" -Dv8_target_arch=mipsel"
+			else
+				die "big-endian MIPS is not yet supported"
+			fi
+			if [[ ${CHOST} == *softfloat* ]] ; then
+				myconf+=" -Dv8_use_mips_abi_hardfloat=false"
+			else
+				myconf+=" -Dv8_use_mips_abi_hardfloat=true"
+			fi
+			if [[ ${CHOST} == *loongson* ]] ; then
+				myconf+=" -Dmips_arch_variant=loongson"
+			elif [[ ${CHOST} == mips*64* ]] ; then
+				die "generic MIPS 64bit is not yet supported"
+			elif [[ ${CHOST} == mips*r2* ]] ; then
+				myconf+=" -Dmips_arch_variant=mips32r2"
+			else
+				myconf+=" -Dmips_arch_variant=mips32"
+			fi
+			;;			
 		*) die "Unrecognized CHOST: ${CHOST}"
 	esac