3 rd ignition wire question?

hello again, i have three ignition wires my remote start only has two ignitions output wires. So i need to add a relay right ,  but the remote start does not have any neg output during remote start or anything like that...   Any help to add a relay to make this work??      is there a way to tap into one of the other ignition wires and add the third relay?   thanksFactory security systems suck!

what car and what alarm do you have?"I'm So Loud It Hertz"

yes, you just add a relay and use one of the two existing ign wires to turn on the relay which will then send 12V to the third ign wire