How to integrate a seam into an existing project. Or vice versa

The best approach is probably to add the Seam library to an existing project and then gradually refactor your code to take advantage of Seam's features. To do this, follow the Seam Guide and edit your code for each seam function, which will simplify the JSF approach. This includes things like:

• Make your JSF action listeners into Seam Components (i.e. add one annotation)
• merge action listener and EJB classes (action listeners can be EJB in Seam)
• inject Persistent Contacts persistence context instead of your existing Hibernate session
• simplify page navigation rules using Seam Navigation Simulator
• transfer views to Facelets if you are still using JSP.

Basically, Seam will probably give you many ways to simplify your existing code, so apply them one at a time to see how they work.