Do this simple test for us. Using your browser go here: http://www3.limewire.com:6346/ The page should say 'Your test worked!'. What happens when you go there?

If your friend can't get to that page then it means that port 6346 is blocked for some reason. Be that via a modem/router or your isp or even a firewall.
Use this as a guide to configure your firewall: http://www.limewire.com/english/content/firewalls.shtml

If your friend's port 6346 is blocked then try another port like 3500 or 20282 The way to see if it's open is do this test: http://home.no.net/tgrumpy/ct/dex.php & choose change the test port no.

What type of router/modem does your friend use? Brand & model no. would help!