Searching google for "seam example jbpm" gave me this link: http://www.redhat.com/docs/manuals/jboss/jboss-eap-4.2/doc/seam/Seam_Reference_Guide/Seam_Tutorial-A_complete_application_featuring_Seam_and_jBPM_the_DVD_Store_example.html
there you can read this:
The administration screens take use jBPM to manage the approval and shipping cycle for orders. The business process may even be changed dynamically, by selecting a different process definition!
Checking this example will get you started (it helped me a lot), you can also use seam-gen to create the app skeleton for you.