http://blog.litot.es/2006/03/02/boot-from-cd-in-open-firmware/

http://mac.linux.be/content/guide-open-firmware-apple-bios-0

Digging around in Open Firmware I get closer to booting OS9 from my Powerbook G4 1.67:

0 > boot hd:,\Mac%20OS%20ROM load-size=2aad16 adler32-6fa3f548

parsing

Bootinfo is not supported

0 >

So I need to edit the CHRP-BOOT section for sure, but this is really good news (so far). It means that the OF system chooser (Booting with option held) is actually *reading* the Mac OS ROM file and throwing it out on purpose....