Most tire shops/full service shops should have the tool. It's not a very complicated tool, but it just needs to do like several hundred different cars from every vehicle manufacture.
GM's are so easy to get into learn mode. Car in park, KOEO and hold "lock and unlock" on the factory key fob for 5-7 seconds and that'll set it off, horn beeps and the info center will light up. Just don't do it without the tool haha, because it will make everything a "--" for pressure and keep the light on.