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.