An actor would play as a character and interact with other people in the area, this could be the customers or even other characters. They could act as characters and at the same time be clerks who would be selling the product in a subtle direction. They would also carry the book (used as http://www.ricohclickablepaper.com/) and then sort of break "their" fourth wall and tell "their" story to customers. In this way "both" the "character" and the "customer" are able to interact with each other.
Arena for Books