I mounted the new switch in the location of the old switch button. There is a hole mostly there already if you just cut the remaining plastic to leave about a 3/8" hole.

You'll need to trim down the small plastic posts that held the switch circuit board in place.

The switch doesn't have a lot of threads, so you can't use thick washers. I used a 5/16" speed nut on the inside, which also helps keep the switch centered since hole is a little bit bigger than needed.

On the outside I used a thin plastic washer, then the nut for the switch.

Bend the tabs down as pictured so wiring will fit when reassembled. Tighten nut.