What version of postgres are you accessing? There is an ODBC driver available from the postgres site that works with 6.5.x (and potentially earlier versions). If this is the case, you can use DBD::ODBC (which works exceptionally well for me) to access your postgres database. From checking the ActiveState site, there doesn't appear to be a DBD available for postgres.

I know from experience however that this ODBC driver does not work with postgres version 7.x.

Good luck!
MrCromeDome

Update: Whoops! I appear to have made a liar of myself. Just checked out the postgres site for the first time in a while, and they appear to have a pretty recently updated ODBC driver for postgres 7.x. This might be just what you need. Haven't had the chance to test it though. Again, good luck!