The darwine project didn't really attempt this. The only thing you need to run 32-bit windows apps on powerpc linux is to install qemu. Originally qemu was developed just for this and only consisted of a linux binary loader these days it is also a VM but you can still use the good old binary loader. The darwine guys assisted porting the qemu binary loader to darwin, so that a potential darwin x86 port of wine could be run on the powerpc build of darwin / osx.
