In another posting I described how to edit the system-jazn-data.xml in order to create a user.
To my astonishment there seems to be a possibility to create these users using the Application Server Control.
Here are the steps:
In the ASC cluster topology click on the OC4J that contains the javasso.
Click on Applications
Click on the module javasso-web
Click on Security provider
In the realm jazn.com click on the number in the users column.
In this screen you can create users!