here's the quick trick I would try.

figure that there's powered LED's that illuminate the fiber optic strands that make everything glow. And its all UNDER the keyboard, not specifically part of the keyboard.

I'd go to an art store, and find some colored acetate thats pretty thin, and relatively transparent. Then, if you've got the moxie, remove your top case (24 screws) and remove the keyboard from the top case. Cut the acetate to shape, and use a hole punch to punch out where the screws need to go through. Lay it in place, reattach your keyboard, and then the top case. When you power up and illuminate in the dark, the light will go through the acetate, pick up its color, and it should make your keys glow that color.

Figure that I've not done this, but at first thought, thats how I'd proceed. At least, it seems the logical way.
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Electricity tastes good. No, seriously.