I posted this over at Scoobymods but thought it may be of use over here.
I had to replace my backlight bulb in my cruise control switch and while I was at it decided to change the backlight of the cruise and foglight switches.
Unfortunately, I didn't take a pic of the switch apart.
Step 1: Remove the switch (obviously).
Step2: Dissassemble the switch.
This can be done by inserting a small flat-tip screw driver between the tabs on each side and simply popping the switch apart.
Step 3: Remove the small "lense" of the switch.
After you take the switch apart take the small screwdriver through the back of the button and knock the small rectangle "lense" off the button. It doesn't take much force but I tried to push near a corner to reduce visible damage.
Step 4: Remove the green coating on the back.
I used a pocket knife to scrape it off as much as possible without damaging the plastic. I held the lense up to a desk lamp to make sure the light was shining through constistently. When I felt I couldn't scrap any more, I used some contact/brake cleaner on a rag to give the back of the lense a good wipe.
Step 5: Paint the back of the lense.
I build model cars so I had a small bottle of Tamiya Clear Red (X-27). (It's meant to be used on painting the brake lights on model cars when they are molded in clear.) I used three coats, allowing plenty of time between each coat for the paint to dry.
Step 6: Reattach the lense.
I used a small dab of superglue to the area just below where the indicator light is on the lense. You'll see two openings on the button once you have the lense off. The dab of glue will line up with the small rib that seperates the the two light paths.
Step 7: Reassemble and reinstall the switch.
Reverse of Step 1 and 2.
Step 8: Admire your work. If you did it right you should get orange/red backlighting. (I think it looks red and my wife says its orange. I'm color blind so I'm not sure who's right.)