Well, my coin door has that kind of switch - as do most of them I believe. The long wire, which rotates a good deal, is what the quarter hits when it is accepted by the coin door. if you're looking at the back of the coin mech after it's been attached to the coin door, then place the switch near the bottom(mine is bottom right) so the wire is sticking in the path of a dropped quarter and the switch's side is parallel with the mech - the wire should go up/down. There should be some screw holes - a plastic guard nearby perhaps, too. The quarter should go pretty much straight down if it's accepted, and on the way it whacks the wire which triggers the switch.
hope this helps