I'm glad everything worked fine so far :)
In order to change the persistence of jbpm from h2 to some other data source you need to change the values of the jdbc driver, dialect, jdbc connection url,username, password within testDS1-ds.xml and the persistence.xml, hibernate.cfg.xml files found in the following files,
1. jbpm-human-task-5.xxxx.jar (inside META-INF)
2. jbpm-bam-5.xxxx.jar
3. jbpm-gwt-console-server-5.xxxx.war (WEB-INF/classes/META-INF)
4. testDS1-ds.xml after installation is located in jboss (i.e. /jboss-5.1.0.GA/server/default/deploy/testDS1-ds.xml).
p.s.1 After the installation you'll have to replace these jar files after you've changed their persistence.xml and hibernate.cfg.xml, within the runtime folder that has been created and within the jbpm-gwt-console-server.war that is deployed in jboss (i.e. /jboss-5.1.0.GA/server/default/deploy/).
p.s.2 you might want to comment out after the first run the <property name="hbm2ddl.auto">create</property> found inside persistence and hibernate files , since this property will recreate the db each time jbpm and the human task are restarted, in other words all data persisted in the jbpm db tables will be deleted.
p.s.3 if you use console reporting the birt reports will also have to be edited to point to the new datasource