A youtube video demonstrates a PSP operating on a python build called Stackless Python. No know description has been found, which contains a build, source, or description of building Stackless Python from Source.
Building Python yourself is recommended, as python's core is embedded-ready for different platforms. The main reason is having to ./configure it. One possible method is to acquire a copy of libpython.a and gather the necessary headers for use. This also may require you to copy the compiled python files (libraries) onto the PSP, colloquially install them.
Much functionality that Python offers will be lost. Although, the basic and non-net libraries should work.
Editing of the python source may be required, for example, on windows with mingw64/32 %zu doesn't exist when formatting strings. Every error and printout it seems uses %z*.