Maybe there's not a step-by-step on how to do that, but if you know how do cabs and arcade boards work, it contains more than enough info to do it. Check the pin-out in the manual scans.
As I said you just need to connect the button you want to use as D to pin 25 (and the second player one to the same corresponding pin in the solder side) of the JAMMA harness, next ot the other 3 pins for regular buttons. Wire one of the cables from the button there, and the other cable that comes from the button to any ground spot in the cab.