Contrary to common belief, Zip disks are not meant to act as hard disks. I would recommend that you not try to add your Zip drive as a shared folder as the queries and downloads are going to put a lot of strain on both the drive and media. If it were me, I'd mount the Zip disk and copy the files to a directory on one of my fixed disks.

As far as the mechanics of copying the files to your current LimeWire shared directory I'll let a Windows person advise you on that.