This is an ebuild candidate for the Perl module HTTP::Request::Form, which does not currently have an ebuild. I tested this out and it works.
Created attachment 23689 [details] Ebuild for HTTP::Request::Form
Bob: Gentoo's current policy is that if a perl module doesn't fill a dependency for an application, we can't add it to portage. This is so that the portage tree doesn't grow wildly (and to try and limit maintenance overhead). Does HTTP::Request::Form fill a dep of something in portage? (For perl modules that don't have ebuilds, g-cpan.pl will create ebuilds on the fly and install them from CPAN.) Either way, thanks the submission.
No, this isn't necessary for anything that currently has an ebuild. I use it for my own development. I have an mail filter that involves querying a webserver to provide supplemental information in the mail, and some programs that automatically walk-through Wal-Mart and Sam's Club photo centers in order to download pictures. However, neither have an ebuild, and I'm not sure that either ever will, at least not in the official gentoo distribution (maybe in a local overlay here at work).
Ok. In that case, g-cpan.pl should do the trick for installing this for you. Closing bug.