06 Ram add-on starter

I am wanting to use a add-on remote start on a 2006 Dodge Ram pick-up. I am looking for a way to get just the lock signal to activate the system with-out the unlock activating the system also. Has anyone done this? If so, how?

STart with a unit made for this purpose. It usually doesn't come with a remote and for that reason it's a little cheaper than others. I've done a few and they work pretty slick, only drawback is the range. Most people like to start the vehicle from a good distance and factory keyless remotes lack that. Most are about 30-50 feet. I usually try to talk people into buying a start/keyless unit and just setting aside the original remotes.Steve G