Just ran across this - thanks for posting.
BTW, there is a brief write-up on doing this for an older Focus on FocalJet
I was planning to try this over the holidays, but then I realized - As designed, the door and window switches only light up when the engine is running. When the engine is running, I typically don't want to open the trunk. When the engine is off, if I open a door, I can see where the hatch release button is b/c the dome light comes on.
So for me it wasn't really something I would find useful.
What I would like would be lighted cruise control buttons, but I think those are just painted on and would be REALLY difficult to do.