Production Switchers

We are trying to chroma key someone that is using a touch monitor that has some green on it. We have the Carbonite and seem to be struggling with the best setup. We have tried to build a ME with green behind the monitor so it keys green back in but never looks clean enough. We tried to key the source back on top of it and use a mask and the delay when moving the arm was noticeable. Any Recommendations with the Ross Carbonite, we do have a xpression if that could help with this also. Can we create a still that has alpha where the monitor is so it is doing a chroma and auto select key? 

Can you send me a link to a still capture of the Camera and Set --- Then a capture of the "composition" of the output.

The first one might let me try to mimic what you are doing with the still to see if I can solve it.  This should be possible with a Mask and a Force mask...