The easiest way is to tap the wire in the driver's kick panel, I want to say it's the red/black one in the bottom white 20-pin plug assembly.

This will give you power to your gauges when you turn on your parking lights or headlights only, and they are off when your lights are off.

I can get the right wire if you need it, all I'll do is remove my kick panel real quick or you can get a $3.00 tester from Radio Shack that will light up when you test the pin in the assembly and your headlights are on, that's what I did.

2004 TJ "X" - 6cyl.|5 speed|2.5" Skyjacker Lift|Skyjacker Nitro Shocks|Chaparral 33's|Cragar Soft 8's