Download from https://sourcery.mentor.com/GNUToolchain/subscription3537?lite=MIPS
FAQ at https://sourcery.mentor.com/sgpp/lite/mips/portal/target_arch?@action=faq&target_arch=MIPS
Home page for the free (lite) edition at http://www.mentor.com/embedded-software/sourcery-tools/sourcery-codebench/editions/lite-edition/
source ./env.sh
Pseudo-instructions: http://en.wikibooks.org/wiki/MIPS_Assembly/Pseudoinstructions