It's dead easy. You don't have to crack anything open or use duct tape. When you get the electrical part out, there are two small bolts on the black plastic housing, but they are rounded over. Security bolts of some kind. I took a dremel and ground a slot into each one, then just used a regular screw driver to remove them, but placing the flat head into my custom slot on each bolt.
Separate the two parts, move the new electrics over to the old mechanical key part. Re-combine. Re-insert the bolts with the slits. Done.