This link will tell you how to enable UPnP. Don't worry that it's talking about Panasonic products!! It's a nice simple guide for UPnP Once you've enabled it, within LW go tools > options > advanced > firewall config. Tick 'use UPnP' & apply. Give LW half an hour to settle down & see if the firewall disappears.
http://panasonic.co.jp/pcc/products/...ys_wrt54g.html

Now if that doesn't work, the next step is manual port forwarding. The link below has all the info you'll need. Just remember to set up a static IP address, you'll see the prompt on the portforward page. If you skip this step then p/f won't work. Again, once you've set it up give LW half an hour to settle down.
http://www.portforward.com/english/r...G/Limewire.htm