The right way to hard wire an inverter for what you are trying to do is to cut the cigarette lighter part off, take the ground wire and connect it to ground like you would an amp, then wire the positive wire to a SPST relay, then the input to the relay from the battery to a fuse holder then to the relay input, then you wire the coil contacts of the relay one to ignition + and the other to ground.

Notes: you want the fuse to be as close as possible to the powersource (the battery). For the igniton + you can use the wire that turns the radio because the relay has very low current draw.

 

wow its pretty technical in hear. I just put the inverter in the armrest , drilled a hole at the bottom, and ran the wire to the glovebox. No wires visible either.

 

Got any pics??!!??