Thanks Maciej ;)
In the meanwhile (before your previous post) I was using the human-task-core.5.4-Snapshot and the jbpm-flow.5.4-snapshot, both from yesterday build... and it was working with the LocalHTWorkItemHandler. But I don't think it's a good ideia to use some parts of 5.4-snapshot and others from 5.3-final.... so I reverted everything to 5.3-final and used the GenericHTWorkItemHandler. It works.
That's what I do:
....
LocalTaskService localTaskClient = new LocalTaskService(taskService);
GenericHTWorkItemHandler handler = new GenericHTWorkItemHandler(kSession);
handler.setClient(localTaskClient);
handler.setLocal(true);
handler.setIpAddress("127.0.0.1");
handler.setPort(9123);
kSession.getWorkItemManager().registerWorkItemHandler("Human Task", handler);
handler.connect();
....