It's a good thread. I think we should give it a more exact title, what do you think? It would be great to see many people there.
So, first of all I think Walter scared the hell out of the people in Tull. They were afraid of him and when Roland appeared... their fear and confusion became even more hysterical.
The fact that he could make Sylvia choose the red was an important point to be able to lead the people there because Sylvia was a woman who could convince and and put pressure on people. Sylvia was his puppet who did the main part of the game.
And with Alice - I think it was just some kind of really hard hypnotism. Child's play for Walter.