I'm afraid I must differ with you on the self-containedness of libwww-perl. From the README:

In order to install and use this package you will need Perl version 5.004 or better. Some modules within this package depend on other packages that are distributed separately from Perl. We recommend that you have the following packages installed before you install libwww-perl:

URI
MIME-Base64
HTML-Parser
libnet
Digest::MD5

While they say "reccommended," I was unable to install libwww-perl until I had the first three modules above.

HTML::Form does seem to be a good place to look, though... I'm not sure how I missed it (lack of hierarchical information, perhaps?).

amelinda