Just connect the compressor to the Horn wire and ground the ground wire. Hook up the tubing and you are done. We mounted ours in the mouth. There is a bracket inside just waiting for your installation and a 10MM bolt.
Note the stop lights and horn are on the same fuse. If you have no horn,
you have NO STOPLIGHTS! Always carry a spare fuse, you can buy fuse kits for under $5.00.