Is it possible to have an ipcop machine connect to the internet through

a passworded proxy? So i can tell it somewhere somehow to connect to my

gateway (which i've done) on port 8000 with a given
username and password? (cant find and option for these). Putting it
between the ISDN and the gateway isnt an option. I'f theres another
firewall which allows me to connect through a passworded gateway then
i'd be willing to try that. Thank for any help.