Now that official CD images will be bootable, I think the FAQ should
be updated - it currently suggests a netboot setup as simplest way
to bootstrap NetBSD/sgimips - IMHO booting from a CD, following the
instructions in 

ftp://ftp.netbsd.org/pub/NetBSD/NetBSD-2.0.2/sgimips/INSTALL.html#Install%20via%20a%20bootable%20CD-ROM

(or a 3.0 equivalent, once it becomes available) should be the first
suggestion in 

http://www.netbsd.org/Ports/sgimips/faq.html#bootstrapping

Martin