Can a dealer install the V92 Tow package

[Dave]

I bought a new 2012 enclave over the weekend. One of my requirements was the car needed to have the trailer towing package so it could tow up to 4500 pounds. None of the 2012's at the dealer had the factory installed trailer tow option, but the dealer said he could install. Parts are on order and he is to do it this week. He says there work includes everything they do at the factory. However reading the manual i have become concerned that the dealer can't install this option (there is not a tow/haul mode button on my car), and the Vin does not include the V92 info. Can the dealer install? And will GM honor my warranty if i have a problem? What are the parts that need to be added to have it covered under warranty at the 4500 lbs.

Any help would be appreciated