I am preparing to install Debian on my dual-G4 system. I even have a spare partition I can put it on (I don't have any desire to get rid of MacOS or the various partitions I have made to deal with it). I was hoping to follow the instructions in http://people.debian.org/~branden/ibook.html but it seems that thepartition must be the first on the drive. It also seems that only yabootcan be used as a boot loader.
Not true, you can just reorder it when setting up your debian partition. See this article for good detailed instructions...
http://penguinppc.org/projects/yaboot/doc/mac-fdisk-basics.shtml(and another good one on yaboot is on penguinpppc.org, these were a big help for me)
Jim M