how to add air horns to alarm output wire

Recently installed a CoadeAlarm CA1151 alarm, got everything installed fine. My question is how to add air horns via the horn output from the alarm brain? I know that there are diagrams about adding air horns to the factory horn, but I want to have them "honk" only when the alarm goes off. Instead of connecting the horn output wire to the factory horn, I want to connect it to the air horns.

The alarm has a -300mA output wire designated for the horn, and I can change the pulse times as needed, but exactly how would I hook this up to a relay? Since the wire has different pulse settings I assume that I dont need a flasher like I would if I were hooking the air horns thru the alarm siren, correct?

Any help is gratly appreciated......