Besides a few layers of tape and hoping a little vibration doesn't loosen the tape slightly. I'm looking for a way that is easy to take off and not likely to damage the switch over time from repeated use. Any ideas?
I just either electrical tape or this thin yellow Tamiya masking tape used for model painting. It's about 0.2" wide, and twice around holds the button down flawlessly, and it's just masking tape so it doesn't stick bad enough to leave a residue or FUBAR your bottoms. I highly recommend it. I use it to take all my beam shots or look down at the beam.
you can find the double-sided stuff at some hardware stores,it just wraps around itself and grabs on tight...
Or you can get the much-easier-to-find adhesive-backed stuff and tape the hook side to the loop side and you're done.
I have some double sided velcro I'll send to you if you want.