I could have sworn that Debian supported Old World PPC machines(I know they support 68ks)
Debian does support Old World Macs, but you have to make sure that you copy over the kernel and ramdisk image to the Mac OS partition before you reboot after the installation finishes (assuming you use BootX). Otherwise, you won't be able to boot into your installation. It basically requires that you know which partition under GNU/Linux is the Mac OS one, load the respective modules (depending on which HFS filesystem you chose), mount the Mac OS partition, and then copy over the kernel and ramdisk with "cp".
As a matter of fact, I even did this with Ubuntu and it also worked. However, Ubuntu has a lot of overhead that older stock Old World Macs might choke on.
Also, as of Debian Etch support for 68K Macs has apparently been dropped.