adding GM keyless entry to '04 Blazer

I just got an 04 Blazer with almost all of the goodies.... except it was a rental unit, with no keyless entry. No RCDLR (receiver) installed, just the wiring harness plug for it. If I get a receiver and key fobs (and program the receiver for the key fobs), do I have to use a tech 2 scan tool to tell the BCM that it has keyless entry??? I am assuming that I would need to since the class 2 modules send a SOH every 2 seconds, the BCM probably needs to be told the vehicle is so equipped. Or will it just learn when it hears the RCDLR on the data buss and unlock the doors when the command is on the buss??? Ya gotta love all of the wiz bang stuff on the newer vehicles!!! Thanks for any insight, the sevice manual is somewhat vague.