Piezo Siren Wiring

With a Viper 791xv how would I wire up an in car piezo so it will only go off when a full alarm is triggered (no warning chirps or soft chirps).  I have read every thread on this and have not found an answer.  Some people wire it to the doors but when the door closes the piezo will turn off and if the door is left open the battery will drain.  The only reason im not hooking it up with the regular siren is because supposedly the piezo sets off the shock sensor with warning chirps. Thanks a lot.

I was looking at the manual and came up with this:  Change the feature 1-12 (Horn Output) from pulsed to constant and leaving feature 1-13 at Horn function Full Alarm only. Can some one help me setup up a relay for this. Thanks