in reply to
Submitting a form
Also, this might also be a little bit more to set up than you're looking for, but HTTP::Recorder can record your actions when you interact with the web site normally (through your browser), and produce a WWW::Mechanize script.
Even if you're planning to use a plain LWP::UserAgent rather than Mech, the script that's produced will tell you what the values are being set to as they get sent back to the web site.
If you have any problems with HTTP::Recorder, feel free to /msg me.