Excellent, keep the suggestions coming!
I've thought about using the Opti-Pac left/right mouse buttons as admin buttons... However, on the control panel I also four more buttons: "Left Mouse Button" and "Right Mouse Button" (two sets of these wired together, so really its only two buttons).
Now, I was going to wire these to the Opti-Pac, but I could wire them to the same player 1 button 1 and button 2. That would mean I have four buttons wired to "player 1 button 1 and button 2" but thats OK.
If I did that, I would free up Mouse Left / Right on the Opti-Pac...
Phew, anybody understand what I just said?

What would you do in my situation:
1) Remove player 1 and 2 button 7 and use those extra two buttons for the admin functions.
2) Connect my current mouse left + mouse right buttons to player 1's button 1 and button 2. (thus freeing up mouse left / mouse right and using those two for the two admin buttons)
3) Ask Andy about one-button shift-key wiring. I'm a bit clueless on this, but if I talk to Andy I could probably figure it out.
I'm leaning more towards option #1, but I'm really worried that I'll run into games that require 7 buttons per player. Are there any of them like this?