Any chance you could post pictures of your foot lighting and your setup? I've been wanting to do the same exact thing and I wonder if you have any good tips.
As for your question, I'm sorry I can't be too helpful because I don't know how they're mounted. If they are surface mount LEDs (many backlit panels come as circuit boards) they might be tricky if you don't have a lot of experience soldering SM parts. If they're just through hole, it would be just a matter of selecting the right size LEDs and plugging and playing. I will say though that blue LEDs aren't great for vision, it has to do with the wavelength of the light and your rods/cones in your eyes. You lose contrast, which may or may not be annoying for you. I would do a test to see if you like the effect first before doing a total replacement.
