Port Forwarding / Home Routers
There are quite a lot of home routers out there, so giving a guide for them all would be quite difficult. Heres one for DD-WRT (I run a linksys WRT54G).
Open a browser window, and goto your router's IP address. In most situations you'll find this is your default gateway. You can find this by going to Start > Run, typing "cmd", clicking ok, and then typing "ipconfig" and pressing enter.
Click "Applications & Gaming"
Click "Port Forwarding"
Click Add
The following settings should be enough: Application = LFS, Port From = 63392, Protocol = Both, IP Address = Your Local IP Address (can be found from ipconfig, as above), Port to = 63392, and tick Enable.
Click "Save Settings"