99 gmc serria locks, auto pager

It all depends on which style truck you have, old or new, if old style which cab style, 2 door or 4 door, and if it came with factory remote keyless.  New style truck is Type A, old style truck can be either Type A or Type C.

Check out the Bulldog Web site at :    http://www.bulldogsecurity.com/bdnew/vehiclewiringdiagrams.asp    and look up your truck.  Then look for the wires at the locations they list.  Use a DMM to verify the wires.

I am not familiar with the AutoPage R/S's,  but Type A should be no problem to hook up.  Type C might require relays.  

If you have Type C, check out the Door Lock Relay Wiring on this site for 5 Wire Alternating 12 Volts Positive Door Locks at https://www.the12volt.com/doorlocks/page3.asp#5w.  Scroll down to the correct diagram. 

This Bulldog install manual has a nice diagram of the relay install on Page 9, Type C.  http://www.bulldogsecurity.com/pdf/RS102_112_122.pdf   You can just buy the individual relays and wire them up using your R/S's (-) lock/unlock outputs and connecting to the correct wires on your truck, you don't have to use their "778 Relay" kit.  You will need 30/40 amp SPDT relays and a fuse holder.

Some R/S units can support this style of locks directly (Type C) without extra relays, like Bulldog RS1100 and DEI ReadyRemote 24923.  I am not familiar with the AutoPage unit and can't find an install guide for it to help.

lock - light blue (+) @BCM

bcm is located behind the drivers side of the dash.

if the autopage unit only has negative outputs, you need 2 relays and wire them like so

85 - lock or unlock