Figured I'd throw this up here in case anyone was interested in doing something similar on their bike. Works awesome, I do one for all my bikes. Soldered into a standard garage door opener. Sealed it with heat shrink and secured it with velcro to the bike. 19mm hole for the pushbutton which came with an O-ring to weatherproof it. I added a bead of caulk on the underside for extra protection.
This is the switch used:
www.digikey.ca
It comes in a glossy finish but I got a tip from a member of another BMW forum who suggested to use Scotch Brite on it to remove the gloss finish. It worked pretty well to get it to more of a matte finish.
This is the switch used:
PV1S64011 E-Switch | Switches | DigiKey
Order today, ships today. PV1S64011 – Pushbutton Switch SPST-NO Anti-Vandal Panel Mount, Front from E-Switch. Pricing and Availability on millions of electronic components from Digi-Key Electronics.