Hello Michael,
You might have already found the XML format, but you can find the XML example in the Enterprise Architect Example model:
1. Open Example Model
2. double-click the 'Model Based Add-ins' Navigation cell in the default diagram
3. click the MyDemoAddin class and then click the ShowPropertiesList method in the Class
4. select 'Develop' Ribbon | Behaviour button | Edit Internal Code
HTH,