Well, it has been a fun week of getting mail. Yesterday when I got home from work the Nintendo button holders I bought from a VAPS member ($12) had arrived. They would have been $37 shipped from Mike's Arcade so I decided to go the used route. No one will ever see them and they are original parts!
The shaft of the button will go through the hole in the metal and trip the microswitch lever. These things are pretty funky.