Did this mod today.
Wanted to be inventive, so I got hold of some AAA Li-ions to make the pick look more original, (these are rated at 3.6V but deliver more when their hot of the charger. since these can hold the amperage better than alkalines I thought that it might be sufficent) and decieded to add a nut and bolt to fix the pick with.
The parts used(excluding batteries)
I cut a piece of wireconnector (don't really know the english name for it, we call them "sugarlumps here in Norway) to get a small square nut, and sanded it down with my Dremel.
I then had to make the hole in the front bigger, this was a labourintensive job, and not recommended at all... Fortunaly the sun was shining so I could work on my tan at the same time

. I used needlefiles, a sharp knife and a small flat screwdriver (as a chisel)
I used superglue to fix the nut in the hole. Was a little sloppy and used too much glue. some came on the threads, and I had a hard time screwing in the bolt afterwards. This might have been a blessing in disguise, because this helps hold the bolt in place when the bird "humms"
All done and the battery inserted. I bought this battery from a dealer in Hong Kong.
The finished product. It works, but as the others have noted best on cheap padlocks.
I made a video of it opening a padlock as well, but had some problems converting in Windows Movie Maker
I'll see if I can fix it and post the movie later.