Grab the TC Console application from developer.tandberg.com and look at the layout control options. Compositing will not work on the C40, but layout control will.
A custom layout will do what you are looking for. And the TC Console application even saves the layouts to the codec so that it's easy for your Crestron to invoke them.
Collaboration Technology Group
The opinions expressed in this forum are my own views and not those of Cisco.