most of the new ones are battery operated and run off double or triple A's so powering it wouldn't be a problem.
but i think you should listen to those hints and not do it. think about how a cop's gonna react if he pulls you over and you have one mounted to your handlebars.
my advice would be to figure out all the laws in your state, then obey them as best you can. (unless you have a bike capable of 50+, then get the detector