POST redirection is possible.
It's even NECESSERY if you want to post on some (IIS) server poorly configured, despite what the RFC says.
(we had to do it several times at the office when multi-posting on the web...)
In my memories it involved handling a 'redirect_ok'(!?!) method,
but a quick look at the version installed on my box leads me to rather say that's now(?) the answer is :'UserAgent->requests_redirectable'.
(anyway you might want to see this old post)