When TPMS sensors sit on the shelf their battery is turned off. The sensor itself has to be "woken up" to let the sensor know its in service. Anything with the car's battery won't do much.
The green wand pictured about is about as effective as a blind squirrel is at finding a nut.
NAPA has an awesome tool, but it runs like $1200 bucks. Find an NTB, Merchant's Tire, or Tire Kingdom near by they all had these tools instituted about a year ago. The process is very simple, fast and for about $40 way cheaper than what the dealer will bend you over for. If you really want to trip them out tell them to enter the code TPMSR4 on the work order.
Yes I work for the company, but I'm far from their biggest fan and this is one of those few tools that really impressed me in how well it works.
That said I (heart) GM TPMS systems, they are so straight forward to reset, and they were the first to do away with aluminum sensor (horrible corrosion/breaking problems) to go back to a more normal rubber stem with a "tail" to mount the sensor to. Certain Honda systems get a close second with their modular aluminum stems that when they corrode (they will, they all do) they're not one piece with the sensor and can be replaced. $14 service kit is way better than $100+ sensor.