jBPM or other workflow engine

Hi,
jBPM and other BPMs use POJOs to 'back' the workflow -> for decisions  
and actions in the workflow Classes are 'called'

Now, I specify only to call e.g. de.pich.domi.MyClass. A POJO which  
only must be on the class path... this doesn't  work with Classes in a  
OSGI Bundle, does it?

I guess i'd need 'proxy classes' outside the framework which in turn  
call into the service?

Regards,
Dominik