I used a method quite similar to the one Tim linked. In my case I made a short pin chuck to drive the Maglight body and supported the other end with the live center. I removed the plastic light fixture first.
I then made a pair of bushings, one out of 6061-T6 and one out of Delrin for use on the wood lathe and like on the metal lathe, supported the other end via a live center.
I support the lamp end with the live center and the bushing/pin chuck is long enough to fit inside the ID of the Maglight past the threads.