It's a waterproof case that velcros to the handlebars, and comes with an electrified stylus so you can use the screen through the clear vinyl with gloves. There's also a hole for the cable to plug in my helmet headset.
i use Tom Tom, but it doesn't allow me to put in waypoints. Does Navigon?
I wouldn't mount it period. I didn't mount mine to use as a golf gps in my golfcart. They are not designed for all that beating. My ipod 30 gig locked up every time I mounted it to the handlebars with a RAM mount. So bad intact Apple replaced it.
IMHO I just wouldn't do it.