While not being precisely what you asked for, nevertheless I think you might benefit from some of the replies to these threads:

Analyzing large Perl code base.
Becoming familiar with a too-big codebase?

And you might also wish to have a look at DoxyFilt* (Doxygen for Perl).

HTH,

* Update: 2005-12-28 Kudos to both john_oshea and tfrayner for alerting me to the fact that my link above has been rendered usless by the foul creatures known as spammers... I have found what appears to be a good link to obtain DoxyFilt; the most recent version seems to be from August 24, 2005: Doxygen-0.84.tar.gz. Thanks again, guys!