For starters here are my experimental gcc-3.4+glibc-latest Stages. If you want to use them, make sure you change /etc/make.profile link to point to existing profile, since I used customized thing in portdir overlay in order to build these. Also - make sure you unmask gcc-3.4 and glibc-20040420-r1 at the very least. Otherwise you are in deep trouble. Easiest way to do that is to create your own portdir overlay.
If you think I should add something here, drop me a line. Or bug me on IRC - but mind you - I'll bite your head off.
If interested, you can find some of my non Gentoo/MIPS related stuff at my company site
Here is an ebuild for GNU binutils (as opposed to H.J.Lu's hack-ups). You need to have these to, i.e., build working IP27 kernel (lmo CVS, >2.6.6). Ebuild needs some more work, of course. i.e. it should block default binutils, and such. Or binutils-config should be used to select between them.. Is there a doc on that?