You don't tell us what the "some reason" is that Mozillla::LDAP doesn't build for you. Looking for Mozilla::LDAP, it seems that it lives in the perldap package. Looking at the reported bugs for perldap, as linked from that page, there is a patch to make it work with Perl 5.6.1, and I guess that that patch will also work for Perl 5.8.x.

Maybe the vendor of your linux distribution also provides a prepackaged perldap package?