after rereading the last few posts I just want to say a few things
1. antenna modulators are super sensative and in general are a bad idea. the only way would be to appropriatly shield the power wires. you can try aluminum foil but in reality you need real metal shielding which is more trouble than its worth.
2. I suggest getting a regular 2 or 4 port charger like the one i had and taking it apart. make sure you check the positivie and negative poles and solder them directly. you should be able to run it to the cigarette lighter. it is hard to give advice on the internet w/o physically looking at it, but this is the best i can come up with so far.