I suppose it would
technically be possible to use magnets, but I think it would take a lot of modification to the mod to make something that would work. Here is a pic of the P+ button assembly
The spring rests on a small ledge near the outside edge of the button assembly and on the other side pushes on a small ledge on the ID of the tube just under the battery. When pressed, the whole button moves up to contact the bottom of the battery. Adding magnets to one of these mods would be a rather large customization project, I believe.
I can think of at least one way to do it that wouldn't involve modifying the device itself (custom made magnet on battery, insulated from the tube walls, and a custom made button post with the other magnet on it), but doing so would negate the conductivity benefit of the rhodium plated contacts. That would be a total deal-breaker for me
