I'm (& probably Fury29 also) finding your problem a bit confusing. I don't understand why you'd have the iPod connected whilst you're using Limewire (LW.)
I have a suspicion you're refering to the LW playlist that shows up. Are you using Windows or Mac?
The normal way of doing things with iPod is:
1. Download the songs using LW.
2. Add these songs to iTunes. (if you use mac these songs can be added automatically. In windows, although the LW playlist shows up in iTunes, the songs don't exist within the iTunes Music Library. Songs must exist within iTunes Music Library before you can add them to your iPod!!! Otherwise you're only adding a playlist but leaving the actual songs on the computer. So that playlist won't work unless it's connected to the computer.) See
Adding songs to iTunes & iPod (click on this link.)
3. Connect your iPod & update the playlist. You can update the iPod manually or automatically. I would recommend manually, otherwise iPod will erase its playlist & replace it with what you have on your iTunes. See the link I gave above about links to an iPod tutorial which shows how to do this. There's also a link to an iTunes tutorial & an iPod/iTunes forum.
* (Remember a playlist is simply a file with a list of names of the songs which points to the location of the songs. If the songs are moved from their original location or the playlist is moved to another device without the accompanying songs then the playlist won't work. Updating your iPod copies both the playlist & the songs to your iPod!)
If this answers your question or only part of your problem then please tell us so we can try to solve the other part to the problem.