In this paper we present a novel approach to role modelling for Collaborative Virtual Environments with an Action Oriented Scenario Engine. Our role model is able to take into account different data about the actions such as the abilities, rights or resources required by an actor to determine whether he or she can execute an action. Furthermore, it considers that any data about an actor can have an influence on his or her role in the simulation. We provide also a team organisation model to define the impacts of the rules of the team on the role of the actors as suggested by the role theory. To illustrate our work, we used our model in a Collaborative Virtual Environment for the Training of a neurosurgery procedure.