The solution that I've proposed to you is exaclty that. You can reuse your work items in different processes and you can also attach workitem definitions to your eclipse palette.
Take a look at:
http://downloads.jboss.com/drools/docs/5.1.1.34858.FINAL/drools-flow/html_single/index.html#ch.Domain_Specific_Processes
To see how to acheive that.
Greetings!