If you're using Mac, all you need to do is cjonnect your iPod & it will automatically update with all of iTunes playlists (if it doesn't you'd need to look for the function under File menu for iTunes which says Update iPod.)
For Windows you'll need to import your songs to iTunes. You can just drag & drop them onto iTunes. remember that the limewire folder in iTunes is just a reference to the files in the LW Dwnld folder. They don't actually exist within the iTunes library.
See these threads & apple support tutorial:
http://www.gnutellaforums.com/showth...threadid=31508 http://www.gnutellaforums.com/showth...threadid=31244 http://www.apple.com/support/itunes/...ial/index.html