You not only need to use PowerPC assembly, but you need to use the flavor of assembly favored by gcc/gas (at&t syntax, which is just terrible IMHO). If you're doing stuff inline, you also have to make sure to respect the gcc's ABI for the platform, and don't clobber any registers that it isn't expecting you to clobber.
This is mildly useful, just google "gcc powerpc inline assembly"l:
http://dslab.lzu.edu.cn:8080/members...rogramming.pdf
Keep in mind that really, there are *very* *very* few cases where you would actually want to use assembly language. Most of the time it's not worth it.