You can find the full source code for this website in the Seam package in the directory /examples/wiki. It is licensed under the LGPL.
Enterprise Applicationslist select: jboss-seam-jpa--> Manager Modules --> jboss-seam-jpa.war and set the class loader option to Classes loaded with application class loader first, and then Apply
Enterprise Applicationslist select: jboss-seam-jpa-->Class loading and update detection link and set the class WD1001FALS loader option to Classes loaded with application class loader first, and then Apply. If this setting won't take see the reference guide for more instructions.
For details on these steps and more examples on Websphere including how to get EJB3 applications working see the reference guide chapter Seam on IBM's Websphere.