Video X2

-- Hi everyone, Just wondering if anyone has tried to comp' two moving camera's. The first one starts the shot and renders a 3D set extension it's motion blends into the other camera's motion, that is rendering the video footage of the "Live" set. The effect is to make it look like a single camera move. I am having a hard time figuring out how to get the rendered images of the first camera to match up with the rendered images of the second camera.
Any help would be greatly appreciated.