The easiest way is to buy the adapter that uses the power wired directly from a separate switching power supply that you install. you just attach with a couple of wires. (cheaper)
Otherwise you need to buy one with a built-in AC-to-DC converter.
BTW - how are you planning on doing the CP? Pac's (except for Super) have no buttons. Even if you replace the CP instead of drilling button holes, you'll still have to run wires from the adapter to the CP. you'll have to run wires to the buttons even if you drill, but if you drill, you might as well just put a new JAMMA harness in. No sense hacking the CP and not the wiring...