Not really following your use case. If you like to execute processes without persisting them while they are running what's the purpose of having them persisted at the end (when they are completed)? Since jbpm will remove all runtime data from db once process instance is completed...
I suggested process listeners since that is used to collect information about running processes to build up kind of history log.
If you like to have several elements enclosed in one transaction you could mark transaction boundary your self and jbpm will join that transaction instead of creating separate transactions for each command. Take a look at the documentation for more details.
HTH