documentation about what? Getting jBPM installed? calling a java class from jbPM? building a userinterface?
I assume you need actionhandlers so you can use that term to search for more. One link: http://docs.jboss.com/jbpm/v3/userguide/processmodelling.html#actions
if I correctly understood :
the exemples chown (i.e websale) is for use the jbpm engine as a standalone workflow software(the second option of use of WFMS as mentined in the article "The state of the workflow").
But in the first option we talk bout many exesting dedicated applications and the WFMS will be use to crate workflow between them and create a EAI platform that wath I ask for??