I wish I had a camera... I did exactly that. What you have to do is pop off the needles (make sure you have pics of the default positions) then scrape off the orange coating on the backside of the needle with an exacto knife. Then you have to sandpaper them smooth. You can even ridge them like the angeleyes in BMWs which would look pretty hott. Nobody's done that yet.
Anyway, after you get the color out, you need to put color back in. But now you're doing it with LEDs. You have to modify the gauge lexan plate a bit, and here's where it gets very tricky.
You need to buy LEDs of your choice of color and appropriate luminosity, then wire a couple up in series, and use a resistor so you don't overload the current rating. Then you have to splice them into the rheostat for the gauges so they'll dim with the rest of the cluster. Then you have to shave off the top of the "dome" of the LED. That's where it gets tricky. The LED is basically a "gumdrop" of plastic, and you need to shave off the top so it comes down really close to the cathode and anode of the LED, but doesn't go into it. If you go into it, you can kiss the LED goodbye. You need to shave it off for two reasons. The first is so it will clear the needle when you put it into the hole that you drilled in the gauge face. The second reason is so it diffuses the light more, so it spreads along the needle, rather than staring you right in the face while you're driving.
Now you need to drill the holes in the gauge face (the same diameter as the LEDs that will slide in) and put them close to the axis that the needle rotates about. Then you just epoxy them in and you're done! Colored needles! woot!
It's not a very difficult mod to do, but it IS a very difficult mod to do WELL. Take your time and do clean work and it'll look stock when you're done.