using python to filter requests in apache

Question

I'd like to intercept a user's HTTP POST request using a apache, modify it a little using python, then send it to the regular handler.

Specifically I'll be renaming a POST parameter.

I've seen mod_python has a feature called PythonInputFilter. But I can't seem to work out how to wire it all up in httpd.conf.

1. Does somebody have a simple example of running a python input filter?
2. How is it all set up in httpd.conf?

Thank you, Fidel