You can use 'Guvnor' or filesystem (http://community.jboss.org/message/587133#587133)
You need to modify the persistence (process/task/audit ) details for Oracle.
Do you plan to use JBPM-Console (e.g, http://community.jboss.org/message/587133#587133) or you are planning to use it using api calls (e.g, http://community.jboss.org/people/bpmn2user/blog/2011/04/03/jbpm5-human-task-api-usage-example) ?