tl;dr (Too Long;Didn't Read)
Just don't, not worth the time or money.
The N64 IRIX SDK is part of Nintendo's original development options, although was deprecated by most studios after a few years, because Windows PC had increased in performance and dropped in price.
N64 Development on an SGI Workstation (Any) is not easy. IRIX and it's available software (i.e. Web Browser) hasn't been updated in over 15 years and a 100 to 200 MHz processor is not going to perform as well as a modern computer for compiling.
The only way an SGI Indy (very specific) could be a benefit is if you are using the Ultra64 Dev board that was produced by Nintendo this could possibly allow for source level debugging.