I'm powering a Garmin CS60 from the constant power wire in the headlamp connector on my FE 570. If you check the headlamp connector, you will find one wire that remains powered independant of the high/low beam switch. On my bike, this powers the small 12v emergency light. I pulled the pinout of the connector, and soldered a mini i waterproof inline blade style fuse holder to the backside of the pin. I then replaced the pin in the connector.
I then purchased the 12v cigarette lighter power cable for my GPS, and when it arrived. I utilized my meter to check the output voltage from the cigarette lighter to the input on the GPS. It was 12v, so the GPS was set to handle 12v at that input. After checking this, I cut the cigarette lighter end off of the input plug leaving the right amount to reach the other side of the in line waterproof fuse holder which I had runn alongside the factory wiring loom to the left side switch gear. I installed a 2 amp fuse in the in line plug, soldered all of the connections, and it works perfectly. As a bonus, the headlamp is protected by a factory fuse, and the GPS is further protected by the in line fuse. Gps is hard wired perfectly.
I also wired in a set of Grip Heaters from constant power pin on the ignition key that is fused. If your careful removing the pins from the connectors, they easily acccept a second wire being soldered to the back of the pin, with the pin back in it's slot, it comes out very sanitary.