hi dotan,
as far as I remember you can provide your own implementation of org.jbpm.pvm.internal.history.HistorySession with the <history-session/> tag in the config.
Then you basically do nothing in the process(HistoryEvent event) method. There is a config and example on github that might help you: https://github.com/mwohlf/nchar/blob/master/src/jbpm4/jbpm4.cfg.xml