[particlewave]

Pretty simple if you are handy with a soldering iron. If you just want green, even easier. You will need 3 green leds and a couple 100ohm resistors. Tap two wires into any 12v power source(I just used the existing bulb socket), attach both resistors in parallel to either wire(this will drop voltage to tolerable levels), then mount and wire all three leds(also in parallel).

If you need more detail, just Google "led powered by 12v" to get wiring diagrams.

There are also direct plug and play leds available that you just put into existing socket, no extra wiring or resistors needed, but I don't know if they come in green.