Kate,
Mymo (Parker 27) has a coolmatic compressor and plate fitted, I think by the previous owner (Richard Watson), or it may have been the owner before that. Anyway the plate is mounted on the aft face of the cool box towards the top and the compressor is mounted to the port side of the prop shaft inboard of the cockpit locker on a board. I suggest you ask Richard if he fitted it in case he can give you some pointers. Otherwise I can take some photos of the setup I inherited and post them for you.