gnats access

Hi all
I had a look at "Appendix E dbconfig recipes" but haven't found the 
answer to my question.
Is there a quick way to set up a port on gnats box so it listens and 
redirects all hits to my gnatsweb.pl?
E.g.
http://internal_IP:port -> http://internal_IP/cgi-bin/gnatsweb.pl
I want to give users external access via DNS based on just typing the 
username and password for database access (I know, no encryption, 
poor security). I've already created a subdomain and set up NAPT 
forwarding on our router. It's just a temporary solution.
Cheers
Adam