RE: Booting your PowerMac (from the HD, without MacOS)
I have been asking around the same question myself since I decided to buy a cheap oldworld PowerMac to run Debian on it.
As far as I can tell, our only options (to but Linux without MacOS on a "oldworld" machine) are:
1- quik, which the "faq-o-matic" calls "dead", but according to some works perfectly well with recent kernels;
2- miboot, written by the author of BootX, the most modern program of these two and supposed to work pretty well.
I can't point you to any quik homepage/download site, but miboot is available from the same page as quik.
Cheers and let me know if I can be of further help,