1) Download the BRMS5.3 ER 8 and build it. 
   Note you might have to change the hornetq version from 2.2.2.GA to 2.2.2.Final
2) Install tomcat 6.x
3) Add Postrgess driver to tomcat/lib directory
4) In conf/context.xml add:
 <Resource name="jdbc/jbpmDS" auth="Container"
          type="javax.sql.DataSource" driverClassName="org.postgresql.Driver"
          url="jdbc:postgresql://192.168.116.5:5432/jbpm" defaultAutoCommit="false"
          username="postgres" password="postgres" maxActive="20" maxIdle="10" maxWait="-1"/> 
5) build (mvn clean install)
6) Deploy (copy target/*.war to the tomcat webapps directory)
7) Wait for the app to start.
8) Test by http://localhost:8080/brms-demo/search