Can't you just cut and paste them all from one folder into another.
All you gotta do is select the first file and then while holding the Shift button down go down to the bottom of all you files and select the last one. this should select every file in that folder then you just cut and paste them into the new folder. Just move them all into a folder in your main C:\ directory.
That should make them available to LimeWire and if you create a new playlist in iTunes you can drag and drop them all into the new playlist that shoould ensure that they are available to both prorams. Tell LimeWire that is your sharing folder and every time you open iTunes if that is the only playlist you have, they should instantly show up on there too. you can even delete all other playlists and librarys to make sure that this is the only one you have. If you drag and drop them into an iTunes playlist they will automatically be placed in a iTunes library for you. Just make sure you drag and drop them into a playlist and not into an new library.