Assuming that Julz is right (
), then this might be a bit tricky. However, there are several options. Using a shader would be one interesting way to do it, but probably the worst. The best thing that comes to mind is:
Seperate the screen portion of the model from the gun (or whatever it is). Have this seperate model move to the guns position at the end of every frame (use proc_late()). With the screen model, make several skins for each state of the sceen. This might not work in your case, but it's an option. You could even keep it on the same model, but then you'd have to have the entire skin multiple times which would kill tex memory.
If you wanted to get really advanced, you could create a seperate view that only renders the panel onto the screen model. This would do exactly what your looking for, but would be a bit more difficult to setup.
Once we have the option to render a panel onto a target image, you'll be able to map the screen onto a seperate skin and render the panel to that.