How to access EntityManager from a Dropwizard DAO

I'm using dropwizard 1.0.3 and I'd like to get my handle on EntityManager. Ultimately what I'm after is CriteriaBuilder but from what I've seen this can only be accessed through EntityManager.

public class MyDAO extends AbstractDAO<MyDAO> {
  ...
  method() {
   org.hibernate.Session = currentSession();
   //how to access/create EntityManager here??
  }
}