Hi BB,
 
There's no 'force IP' option in LW anymore, it's been replaced with the option to use UPnP or port forward. 
Lee's post was written back in 2002 & so there have been heaps of changes since then
 
 
What's the problem...are you firewalled, can't connect or are you just wanting to  optimise LW's performance? 
If you have a firewall/conection issue, please post your system details for us. 
System details - help us to help you -> Provide these details when you post!!!(click on link) 
If you're just wanting the best performance out of LW, check out the thread below (the first few posts by murasame). 
A few things to consider while configuring Limewire for optimal performance...