[otrs] Mod_perl2 required for Package Admin?

I was using OTRS 2.0-beta and decided to upgrade to the stable 2.01 version. I am running Apache 1.3.33 on FreeBSD 5.4 with Perl 5.8.6 Using the beta version, I found the Webmail & Calendar features super-useful. To my surprise, when I upgraded -- and I probably did it somewhat "bone-headed" -- I got the error message "Error: Sorry, mod_perl2 is needed by this module!" when I went to run the Package Manager. What could I do to re-install the Webmail & Calendar modules?