If it is using the BPMN2 notation and you can export it using an xml format it should be executable. You shouldn't need any tool for doing that.. just import it into the jbpm designer in our web tooling and see if it works.
my BPMN2 files use a complex notation, with pools, lines, send tasks, receive tasks, manual tasks, message flows etc.
I think that not all those elements are supported, aren't they?
Where can I find a list of useful elements to jbpm?
How should I treat diagrams with elements that are not supported?
There are always ways around for the non supported elements, but have you tried importing the diagram into the jBPM Process Designer (Web)?
if you have issues with that let us know and we will see from there.