I'm confused. According to the FAQ 
http://www.netbsd.org/Ports/sgimips/faq.html#bootstrapping
"Since NetBSD 3.0 the sgimipscd.iso image is bootable"

I recall having to build my own installation cd but it was before 3.0.

I downloaded and burned sgimipscd-3.0.2.iso
but cannot boot from it.

>> hinv
                   System: IP22
                Processor: 150 Mhz R4400, with FPU
     Primary I-cache size: 16 Kbytes
     Primary D-cache size: 16 Kbytes
     Secondary cache size: 1024 Kbytes
              Memory size: 128 Mbytes
                 Graphics: Indy 24-bit
                SCSI Disk: scsi(0)disk(1)
                SCSI Disk: scsi(0)disk(3)
               SCSI CDROM: scsi(0)cdrom(4)
                    Audio: Iris Audio Processor: version A2 revision 4.1.0

>> boot -f scsi(0)cdrom(4)rdisk(0)partition(8)ip2xboot
dks0d4s8: volume header not valid
Unable to load scsi(0)cdrom(4)rdisk(0)partition(8)ip2xboot: no recognizable 
file system on device.

Any help appreciated.

Regards,
Thierry.