Well to my knowledge, the Belkin routers need manual port forwarding. Oh I just discovered they do have the UPnP option but it's not easy to find. See http://www.adslguide.org.uk/hardware...f5d7630-4a.asp as this will also apply to your model. See about half way down the page.

Failing UPnP is manual port forwarding. http://www.portforward.com/english/r...outerindex.htm but you need to set up a static ip to do this which for osx can be done like this http://www.blizzard.com/support/wow/?id=aww01180p or http://www.sonic.net/support/ss/mac/osx_staticip/