I recommend black spray paint. Spray enamel will give the best finish, but has more fumes than spray acrylic paint. Use masking tape to mask (cover) the things that must remain paint-free, like the docking connectors, and the entire rear panel (holes and all). Suspend the dock in the air, by a wire or string looped through the two side vents. Then keep the spray can horizontal, and move your elbow/body and NOT your wrist as you coat the dock on all sides with a VERY THIN coat -- just enough to make it look shadowy. Wait a while (read the can label for how long) and then spray again.. repeat until the dock is evenly covered. Should take 2-3 spray coats for a very nice job. After each coat, CLEAN THE NOZZLE of the spray can, by simply holding it upside down and pressing the button for two seconds.

Cheers