This finally fixes this project enough to be useful. The tool now processes an existing assembly file instead of invoking the compiler itself (so you can control how it's compiled).
This was designed around using GCC, but other compilers probably work. I've included a batch script that will compile a main.c file and automatically process it with the tool. A lot of extra labels and noise have to be removed from the assembler output to make it work in Cemu, so be careful you use all the same compiler flags if you don't use the included script.
The script depends on this PowerPC compiler being available on your PATH.