OK, here is my summary of how he does it, noting that I'm not a professional and also Cesar has been bit on the show. You can push too hard. He uses a "shhhhhh" verbal command while pointing at the dog. And when necessary he will tap the dog on the butt to as he calls "move the dog's mind/attention forward." Also he sometimes will grip the dog in the neck to simulate a correction bite the dog would get from the pack leader.
The best show I saw was when a couple had this aggressive/ territorial dog. He asked for a leash and told them he would go into the back yard and get the dog to take it for a walk. They thought for sure he was going to get torn up. Well, he slowly cornered the dog, using pool chairs and other things until finally the dog got the message who was in charge. He looped the leash on the dog and brought it back. The owners were totally stunned.
Cesar's Web Site