add subscriber following work item category/team area
One answer
Here is an example that does create an approval and also looks into categories: http://rsjazz.wordpress.com/2012/11/30/a-create-approval-work-item-save-participant/ this shows how to use the subsciptions api, however, honestly the API on the server should look very similar and fit right into the code above: http://rsjazz.wordpress.com/2012/08/02/subscribing-to-a-work-item-using-the-java-api/