No problem. The T2-SDE build system supports cross-compilation as well as other ‘UNIX-like’ kernels such as the BSDs.
I recall reading a little about that in their documentation- they mentioned other systems such as haiku. I thought to get a 'bare bones' type system such as haiku or tiny core would be great on my iBook ..and would be a good way to go. But my skills and know how keep hitting walls.
I think with various older (unsupported) models of PPC based machines there are different traps or particular issues in setting up a system ..depending on wot Mac you've got.
I did wonder within the macrumors PPC community we could develop groupings based on models ie iMacs, iBooks, etc that focused on 'How To's' on steps to put together systems that work on ones PPC.
It's not 'building a system from scratch', nor is it a system 'ready to go straight outta the box' - but a DIY somewhere in between kinda thing.