I made one...Bought a programmable garage door opener from Radio Shack for $20. Then bought a little push-button for about $1.50. Just opened the controller, soldered two wires to the button on the controller, and put the button at the other end. (add the new button in parallel to the old button) Then I sealed up the controller with silicone sealant to keep it waterproof. The controller was mounted up under the little triangular black fairing piece on the right side, and the button went under the starter switch on the right clipon. It's worked perfect since I got the bike, in all kinds of weather...and I don't even have to take my hands off the bars to open the doors. If you didn't know it was there, you would never notice it..
Check the attachment for a pic..it's kinda big though..You can see the button there, and the small white wire that goes down the top of the fork..
Meddle not in the affairs of Dragons, for you are crunchy and good with ketchup