Just wanted to post an update since I said I would..Short version: still working on it
I did successfully get passive entry option enabled using alfaobd, and now I have the option to enable it displaying on my radio screen / door lock settings.
I got over to the RF hub behind the rear seat, and I found that, the C2 connector, already has wires populated in the locations, that are suppose to be for the driver and passenger door proximity handle. And the colors matched my diagram. So, I spliced my door handle to the wires, but no dice.
I'm not sure where the wires actually end up, they must be dead ended in a harness plug somewhere. Have to go to diagrams again and find out.
There are also wires populated in the passive-entry antenna locations, and I think I need to purchase the proximity antennas, since my truck is big horn, I think I only have antenna 1 and antenna 2, which are in-cab antennas, utilized for push button start.
I'm very hopeful, and very close. I'm hoping to have this working very soon, and I will do a proper write-up once I succeed.