Right, drawing & rendering to Direct3D is one way. I was suggesting a simpler method that would simply take each open window and calculate a left and right offset based on the windows depth/Z order. (You know how when you open lots of windows in ... "Windows", they start to pile on each other right?), and -then- generating either a red/blue/color composite view of the entire screen or two seperate screens.
So I was hoping that this simplified method would be... "snack-able", but, as has been said below it probably goes beyond that.