I'm still trying to figure this out too. I believe the sills actually use a blue EL strip, meaning you'd have to replace the strip with a blue one (and potentially muck with the power source).

Why on earth they didn't make these green I will never understand. Blue sills with all-green interior lighting would look completely stuck-on aftermarket and cheesy IMHO. Blah.

I wish somebody would come up with a way to do this, because I'd love the lighted sills, but only if they match.