I don't use iTunes, so I can't tell you the actual procedure, but if you do a search in the LimeWire forums for iTunes, you will find lots of info.

However, an option... Set your Saving Folder (the one you download to) to your iTunes music folder. That way, the songs will go automatically into iTunes.

Otherwise, just manually move them into your iTunes folder after you've downloaded and checked them.

Hope this helps.