I did what you guys are trying to do. While there are probably a number of ways to do it, here are some options. It depends how reversible you want to make it.
Ulimate reversibility
Purchase 12V 30A relay at auto store for $5 or less
Purchase lamp harness Pt297-35070LH $20
Switch harness PT297-35070SH $30
Medium reversibility
Purchase 12V 30A relay at auto store for $5 or less
Switch harness PT297-35070SH $20
I chose the medium option. Remove the radio bezel to get at the switches in the center switch bank. Disconnect the plug from the back of the AUX switch. Wire the new switch harness per directions in this post or original post which is linked to in this post. Essentially you need to tap power off the head/marker lamp. This becomes the power used for the backlight of the switch and power used to latch the relay. Find the connector bewteen the harness coming from the firewall and the harness coming from the lights (located on the driver's side right over the wheel well). Cut the harness on the LIGHT side of the connector leaving you enough to splice the connector back on later if needed. If you dont like this option buy a new lamp harness and cut the connector off it. There are two wires in the lamp harness. These are power and ground. The ground I think has a black stripe. Ground the ground to a body ground. Take the power wire for the lights and connect to the light terminal on the relay. You should have 3 more terminals on your relay. One is ground, ground it. The other two are power from battery, so connect to red side of battery. Last terminal is line from switch. Here is it in words:
SWITCH
Pin 1: Illumination Power for "Lights On" indicator light
Pin 2: Ground for Illumination circuit
Pin 3: Switch Power (taken from Marker Lamp Tap)
Pin 4: Line Out to Relay
Pin 5: Ground for Backlit Illumination Circuit
Pin 6: Illumination Power for Backlight
Pin 3 and 6 are taken from marker light tap. Pin 2 and 5 are grounded. Pin 1 and Pin 4 spliced together and then out to relay.
The only thing you have to be careful of is the red/green trace wire. It looks like there is a diode shrink wrapped in line. I expect this is to prevent feeding power to the switch from the relay. If you swap the Pin 4 and Pin 3 wires it will not work since the 12V switch power that comes from the marker lamp tap wont get to the switch if you try to feed it through the red/green wire. So if you think you got it right make sure you didnt swap them.
RELAY Terminals
Terminal labeled 30 wire to positive side of battery FUSE IT!
Terminal labeled 85 wire to ground
Terminal labeled 86 wire to line from switch
Terminal labeled 87 wire to power side of light harness you found earlier
Now aux lights function by way of switch whenever marker or headlamps are on. That way if you forget to turn them off it also means you forgot your headlamps which will turn off automatically also turning off your aux lights so your battery isnt dead
Like I said lots of ways I am sure, but this is a fairly easy, relatively cheap, fairly reversible way.
Jay