Bob Roberts sells a trackball light kit, very easy to install. Of course, you'll also need a translucent trackball. I have a green one in my Millipede. I'm also going to change the button to a green lit one eventually. Here's a quick but crappy pic:
I was planning on putting a green one in just was wondering if they were compatable? If not sounds like the Bob Roberts kit is the way to go otherwise.
As far as compatibility, yes, the CC trackball housing will fit the Millipede control panel, but you will have to run some wires for the light. When I did mine, I just spliced into the coin door lights for power and ground.