Great thanks for the reply back. Never owned a Road Glide, Can I take off only the inner faring easily and tie into the lighter?
You would take the outer fairing off. There are six screws holding it on. It's kind of a bitch to get back on until you figure out how to hold your mouth right. Just cover the fender with a towel or something when removing the outer fairing...just in case. Of course, you'll have to unplug the headlights and the turn signals as well.
The method bissjim recommended is by far the easier road to travel for getting the functions of the GPS unit only, the downside being that you have to have the radio set to the AUX mode to hear the turn prompts, so unless you have MP3's on the GPS, you'll not be able to play music in the AUX mode.
The more complicated option is to get the HD handlebar mounting kit, the NIM, and do some minor wiring changes. The NIM is kind of flakey though...it will allow the Garmin Roadtech 660 (not the regular Garmin 660) to interrupt the radio and give you turn prompts, no matter what mode the radio is in. The NIM comes standard on the Ultra models of the CVO's, but not the RG Custom, or the SG bikes. It can be done, though the HD catalog says that it can't. HD, in their infinite wisdom, put a slightly different wiring harness on the non Ultra CVO bikes that has to be modified to connect up to the NIM correctly. Bissjim can help you out with the details of the whole NIM installation...he is more knowledgable about all that than anyone else I know of.