As far as uploading your model to guvnor, you can just place your classes in a jar and upload it to Guvnor New->Model (jar) I believe. Then build your package. The reason your process does not open in Guvnor is most likely something else, the web Designer is not able for some reason to parse your BPMN2. Are you using the jbpm-installer? If so what version? Need to find out the version of the Designer and please paste your process bpmn2 so we can test it as well.
Hope this helps.