These patches depend on the tbxi library. Install and use it like this:
python3 -m pip install tbxi # Toolbox Imager: https://pypi.org/project/tbxi/
git clone https://github.com/elliotnunn/tbxi-patches.git
tbxi-patches/macmini.py /path/to/MacOSROM -o ~/mac-mini-rom.hqx
Included are the simple PowerPC assembler ppcasm.py and the Preferred
Executable Format manipulator cfmtool.py. Feel free to include them in your
own projects.