An awesome project!!!!I have been thinking do a Simon game (http://en.wikipedia.org/wiki/Simon_(game)) and when I have read your post I have impressed.Indeed I was thinking how to solve the problem (without using a new power source) because all the arcade lighting buttons that I have found works with 12V. As far as I see in your web your buttons are working with 5v. Could you give me some info about it?
Have you done what needs to be done on your house so that we can cooperate?