Ok, then, as an idea of a workflow, it's doable and Jbpm is flexible enough! and i would use the known designer plugins of Eclipse to create the pure Jbpm workflow, right?!
Regarding the Integration, is it a matter of deplyment?! the output of the designer is a Jbpm project, in other words a folder with files inside, do you have any idea about the technique to integrate these files in Alfresco?! is there a standard way for integration?!