This was the most interesting controller to build, as I did not really have anything to base the design on. I had 1UP's Dual Strike hack to start with, but I soon found out that it would not totally apply for me. In 1UP's example, he just hooked up the four yoke buttons to the Dual Strike, and all of the other controls on his cabinet were hooked up to his IPAC. Since I had a stand-alone panel, I wanted to be able to hook up everything to the Dual Strike (less things to plug into The Control Box), which was a total of ten inputs.
The problem I had in the beginning is that there is not just one common connection for the buttons. Let me try and explain better. When you are hooking up controls to an IPAC, you would hook the Normally Open (NO) connection from each button to the IPAC, and then chain the Common (COM) connections one after another, with one wire from the last button going to the ground connection on the IPAC. The Dual Strike is different in that you can connect any two of the eleven button connectors to activate the output of one of the twelve buttons on the controller. (I borrowed the pic below from 1UP and relabeled it for my purpose. Credit for the rendering goes to him).
Every button had at least two different combinations of connectors that would activate that particular output. The hard part was figuring out the right combinations that would work together. Depending on how it was wired up, pressing two buttons together at the same time could cancel each other out, resulting in no output for either button. I played around with different combinations to see what would work. I also had to make sure that I had enough space on the molex connector for every connection. I finally ended up with the combination shown below. The first pic shows how each button on the Dual Strike is wired up, and the second is how I matched each button on the panel to the Dual Strike.
The other thing I did different was I wired the Y-axis (up/down pot) to a separate molex connector. Since no driving games uses the Y-axis on the yoke, I disconnect the yoke from the second connector and connect a Pole Position pedal there to play driving games. The one thing I never fixed was the flashing start button for Spy Hunter. I wired up the +5V connection and the NumLock from the IPAC to the first connector so that I would have a Weapons Truck button for Spy Hunter, but that was before I read everything on the Ultimarc site and realized that I did it wrong.