I bought the same type of reverse glow gauges that are sold on this site and installed mine this weekend. I set them right on top of the factory gauges and didn't even have to take off the needles. One wire gets grounded (I just connected it to the negative battery terminal) and the other one gets spliced into the parking light's green wire. It was really easy. The only real problem I had was feeding the two wires through the rubber firewall. Took me like a half hour to do so. Tried a coat hanger, but used something sharper because the rubber is really flexible.
And if you don't feel like doing the wiring, you don't have to hook it up, you can just slip the gauges in, but take out the factory ones, cause I don't think they will glow. Actually, they might not glow at all if you don't hook them up, but perhaps someone else can tell you if that's true or not cause I'm just guessing. But I'd just wire it cause it's really easy to do, and they look really great, especially at night. It's like driving a whole new car. Just take your time and follow the directions and you should have no problem.