I assume since you are in OSX support you are running OSX, so:

1: go to prefs, in pull down menu under LimeWire. Click on iTunes and make sure the box for "Enable iTunes support" is checked. This should automatically transfer a copy of your music downloads to iTunes.

2: as far as music already downloaded and not in iTunes, you should be able to go iTunes, under the "file" menu, choose import. This will open a window to choose a folder. If your "user" window is not already opened, go there (your name) and click on shared folder, this is where all of your downloads from Limewire are stored. You should see what you are looking for.