Haven't done it, but, if you do (and one of the reasons I haven't), be very careful of the wiring to it. My compressor wouldn't run off the existing 12v circuits, I'd have to install all new wiring, and a flashlight works fine for me setting up the utilities at dusk or dark. My compressor has really long leads with alligator clips designed for attaching directly to the battery; most 12v compressors get their power that way.
Most 12v air compressors pull a large amount of amperage and the wiring has to be of a large enough guage to carry it. I don't believe the existing 12v wiring and fuses are of a high enough capacity to splice into them (if you were going that route) and you would have to pull all new, proper guage wire and install a suitable fuse to handle your compressor. That's one of the reasons that most 12v air compressors have alligator clips instead of a 12v plug...vehicular lighter sockets aren't rated that high. If you have a 12v compressor that has a cigarette lighter plug on it, I would be suspect of it being adequate to top up a 50psi tire without burning up fairly quickly...
