You sound as though you don't know what you're doing. In OSX LW has the ability for iTunes to automatically add (copy) all tunes dwnlded to its own iTunes library. You shouldn't need to do anything. You certainly shouldn't be attempting to drag LW's app or folder onto iTunes. Which icon were you refering to? The one on the desktop or the one in the Dock? I'm confused by your post b/c you haven't detailed your problem very well.

To find the LW app or anything that belongs to it, use Command+S & type in limewire to find LW. If you've deleted it, you may need to re-install it. Please supply more details & answer my Q's.