I don't know anything about gamelauncher specifically, I have only tried Dragon King. DK has Alt Elements, not sure if the other front ends use it, but they probably can. You could set up an element to use pictures of your CP to show which controls to use. Another element can be for game instructions.
I think this may be easier in the long run, a lot of the games might overlap, so you wouldn't need as many unique images to accomplish what your looking for.
I hope this makes some since, I just woke up, and I'm talking on the phone, so this might not make sense at all.

Paul