I used Nurmix's info posted earlier in this thread to rewire mine for my Intellivision II. Had to modify them just a tad so I could actually store them on it - I used the original controller wires. The Flashback is ok - but the controllers are awesome!
Since my wild idea actually worked, I did a blog post about it - my blog link is in the signature, if you want to see what I did, or try it yourself. Could NOT have done this without his generosity to the community!