Here are some pictures...

First pictures are the switch I made. 2 brass plates
with thin plastic between them. velcro holds the
switch to the radio.

Next is the mini MP3 player with the switch plugged
in and unplugged. I added the external plug with
5 minute epoxy.

Next is the plastic mounting plate. Just some plastic
bent to fit with velcro.

The earphones plug in the bottom of the player.