Hey, that's my game! What would you like to know? It really wasn't very hard to do. Multi-coloured LED, socket, clear flipper button, a piece of clear tubing, a washer and a couple of wires connected to one of the lights on the coin door. You don't have to drill out any holes or anything like that so you can always go back to the the ugly original button if you like. The tube and the washer are used to take up some space so the C-clip from the original button stays in place. I believe I used the original start button spring.
I think I got the button from Pinball Life - http://www.pinballlife.com/index.php?p=product&id=3332. I used the same buttons for the flipper buttons and lit them up as well.
You separate the button piece from the outside holder and use the button piece only. It fits the Williams hole perfectly.
This is what it looks like from the inside:
IMG_20161123_181435 (resized).jpg
Total cost was less than $10. Let me know if you have any other questions.
Dino Z.