I think if you simply run makepanda.py (instead of makepanda.bat), it will compile Panda using whatever Python interpreter you used to invoke makepanda.py. makepanda.bat is really just a script file to find the version of Python within the thirdparty directory, so you don’t need that if you want to use your own Python.
But an easier answer might be simply to use the 1.8 version of Panda, which is already compiled to use Python 2.7 and which is really quite stable.
David