Apache 2 mod_rewrite - How to read POST parameters?
Solution 1:
Mod_rewrite will not work on POST variables.
You would need to use mod_security to examine, and possibly run a url-rewriting script, on any POST variables.
Solution 2:
I don't believe that it's possible.
mod_rewrite can only work on the contents of the initial request line, headers and environment variables. Whereas the parameters of a POST request are found within the request body.