You don't need a special QPAC. You just drag the process from the services tab into your process.
In ES, low-level components implemented in Java and high level orchestrations implemented as workflow are handled exactly the same way - they are all services, that you can just drag into your process and invoke.
You can also invoke them identically externally - as Java objects, SOAP, JMS, etc.
Howard
http://www.avoka.com