Alright, I've been trying to solve this problem for a while too.
Bulb painting with Testor Trans Blue makes the little bastards look green...
So I soldered in some blue 5mm led's on the board. Problem with that is it makes a spot light effect... so most of the fan display does NOT light up.
Working on sol'n 3 right now. Using a set of the following:http://www.truckpartsproshop.com/pilot_led_parking_signal_lights.html
They're flexible and conform to tight area.
Let you know results as soon as I do