what iv done on mine, was sand off all the orange stuff of the back where u want to change the color, perhaps leave the redline red? do whatever you like, go to walmart or someplace like that, buy the transparent sulifane, u know that stuff you use for gift baskets and stuff, and glue that to the back of the gauge, and you can then still use the stock clear bulbs. and the sulifane costs like 2$ and works very well, just take your time, glue it down well, and be careful you dont get glue on the front face side. heres a link on dsm talk
http://www.dsmtalk.com/forums/showthread.php?t=89985 id skip painting the needles at first at least. the main thing is, sand off that orange stuff at the back. i had to use 2 layers of cellofane, i sanded off the back, took a piece of cellofane and a flashlight, went in the bathroom, lights off, closed door, and held it behind the gauge and shined the flashlight threw. it wasnt blue enough for me, i tried 2 layers, it was perfect, should work for any color. let me know how it turns out.