Thank you Ted! I had to make some subtle changes in my enviroment, specifically:
1. In your step 4, I added this content to the JBPMorm-JPA2.xml file not persistence-JPA2.xml, as looking at the XSD, there was no entity element anywhere in the persistence element hierarchy.
2. In your step 3, the transient tag seems to go in the <attributes> element beneath <entity class="org.jbpm.persistence.processinstance.ProcessInstanceInfo"/>. I am sure that is your shorthand, but I wanted to clarify in case any less experienced JPA people like me use this in the future. It also seems to matter that this element occurs at the end of the sequence with the other transient elements.
3. I had to change <jta-data-source> to "java:jboss/datasources/jbpmDS" from "jdbc/TestDS1", but I am sure that is something specific to my environment.
I haven't tested the complete deployment yet, but I can now "enable" jbpm-gwt-console-server.war, so I'll consider this question answered.
Thank you again!