Found this thought you might find it usefull

http://www.yorkspace.com/2006/02/35

Blue LED Car Radio Mod
For quite a while, I’ve been looking at the radio in my truck and thinking it would be cool to replace the standard white backlighting with blue LEDs. Now that I’ve finally done it, here’s the write-up on how I did it. Obviously the designs of radios vary dramatically across manufacturers, but hopefully you can get some ideas on how to make your own modifications.