The trackball is explained on this page:
http://www.ultimarc.com/optipac3.htmlFor the coin door you just need to trace the wires from the 2 credit switches to the harness you have pictured. Snip them off at the harness and extend the wires so they will reach your iPac.
You'll have a ground(likely black) and a trigger wire coming from each switch.
Connect the grounds to the ground terminal on your iPac and the trigger wires to the appropriate terminals on your iPac. Player1 coin is 5, Player2 coin is 6.