I am not in the business of making cpu mining software, really.

agran, the sourcecode repo you pointed out is the wallet software. I think it's better to start with some cpuminer fork (either pooler's or Jeff Garzik's).
If any mining pools are offering cpuminer binaries based on one of these two, you can just ask for the source code (GPL requirement!)

the wallet can only solo mine, and that may become pointless at some time. So any CPU optimizations in the wallet would be pointless too.