There is no solution. Limewire sucks for torrents, simple as that. When your roommate gets back have him contact his ISP and get the info needed to connect and if he forgot user/pass for the router, then just reset the router and set it up again including portforwarding for a real bittorrent client. I would recommend either uTorrent or Azureus.

BTW Azureus has ok UPnP capabilities, so if you could get Limewire to connect using UPnP (brick wall gone), then you should be able to connect using Azureus with UPnP on.