I have the Nuvi 360 also and I love it. I have only used it once in the Boxster (Tail of the Dragon trip) because I usually have it mounted in my company car.
I did a cheesy temporary mount which looked great and worked great.
I have an '02 with the cupholders in the center of the dash up high. If you have the older interior Boxster, this won't work.
I extended the right cupholder and then placed the Garmin Mount that comes with the Nuvi inside the cupholder and it wedges in there well. I did not use the adhesive ring supplied with the Nuvi in the bottom of the cupholder, but would recommend it if I was going to use the GPS in there all the time.
I then routed the power cable around the side and fed up under the passenger side rear of the center console and plugged in the power adapter and fed the extra cable under the trim. It came loose a couple of times but that is only because I didn't use the adhesive disc and would be very solid with it and not disrupt the look of the car if you took it out at any time and pushed in the cupholder.
It worked great, looked great etc. The higher position is much safer as far as not looking away from the road as in the other pics where it is lower in the car.
I can take a pic and send to you if you like.
