Hi. So I tried the two root/boot (>Linux Kernels/vmlinux; ramdisk.image.gz) images.
Using BootX, everything works until I reach the Debian/PPC installer which goes on to tell me that "my architecture is not supported". A friend with a similar system got the same error. I've got a beige Power Mac G3 (266Mhz). Model 510. ROM: $77D.45F2 (dunno what this is worth though :)