I think it would be possible, but you'd likely need to drop into the open firmware and type in a magic incantation to make the bootloader think it was a support

I think it would be possible, but you'd likely need to drop into the open firmware and type in a magic incantation to make the bootloader think it was a supported system (don't ask me to remember exactly what that might be. It was a looong time ago, but I did get both PPC OS X and Darwin to run on an unsupported mac clone that had an upgraded cpu. I remember submitting a posting to resexcellence about it!)