FWIW, I'm only able to get IRIX53 working on the Indigo2. Indy kernel panics booting miniroot. Which IRIX CD and machine were the above snapshots taken with?
Also, the Indy sound and input are intermittent and drop events on my machine (mame64/OSX). I have to type slowly to ensure keys register. Do you see this as well?
I also had to modify the source to add EFS install disks since I couldn't get CDROMs to work. Seems chdman expects ISO or it generates something mame is unhappy with. What's the trick?