As someone with a room full of SGI equipment which already runs Quake (and Doom, and Mektar and Tranquility), I can only say: this port to Voodoo on Irix needs to be done. ;)
Just pick any VooDoo supported source port (old enough, from gcc 3.4 days) it might compile as is with very few changes.
EDIT: all of them use MiniGL, damn....
Soon :) Just got MesaFX working with the Voodoo card. Planning to use that as a miniGL replacement.