Auto Lock on an OBS Tahoe?

Please check out the thinking of a noob...

Here's what I got:

2000 Chevy Tahoe Limited, OBS (old body style) with factory keyless entry.  Doors do not lock automatically and the manual doesn't indicate a way to program this feature.  So don't think it's available.  Don't want an alarm system.

Want the doors to lock automatically when I either start the motor or put it in gear.

From searching the site it looks like a DEI 452T module would do the trick.  Hook it to an ignition controlled electrical source and then hook the outputs from this module to the wires near the brake pedal to lock / unlock the doors.  Actually could live without auto unlock for safety.

Sound right?

Thanks!!!!!!

Anybody?  Would the DEI 452T serve the same purpose as the 3 relays shown here?

https://www.the12volt.com/doorlocks/page3.asp#al

Thanks