How to add a local file to a Github based derivation?

Hi, I'm trying to build a derivation for a python app pulled from GitHub that does not have a setup.py file.

Basically my current line of thought is to pull the source code, add my own setup.py to it and then let buildPythonApplication do its thing. But I haven't been able to merge the remote repo with my local setup.py.

What is the simplest way to do this?

Thanks!