Chris: Thanks a mil for pointing me to people.debian.org/~/walters/debian/installer/new-powermac/ - it worked like a charm. The issue was probably the kernel all along.
I now have a working single-boot debian installation and don't have to deal with mac-quirkiness (I was referring to Mac OS when I said "doesn't ship with a compiler") which is a good thing, nor mac-beautifulness, which is somewhat sad, but hey, I have X11-beautifulness (I love xaw). Now I'm trying to get the internal modem to work. lsmod says that 'macserial' is loaded (and 'serial' isn't), but neither pppconfig nor wvdialconf finds a modem. "setserial -g /dev/ttyS*" says UART: unknown for /dev/ttyS0 and /dev/ttyS1. I don't think I'm running devfs. Does anyone have any clues to what I'm missing? Please let me know. Thanks. Sue.