Best way to map dual-panorama to two skyboxes?

So I want to take 3d 360 panoramic video and get it as fast as possible into two cameras. I'm thinking shader(s) that can map the panoramas onto skyboxes. Have one left and one right skybox. The normal skybox does this by assuming the entire frame is one panorama. In my case, the left eye is the top half, right eye the bottom half, of a square frame. Using Easy Movie Texture to play movies (will be for mobile).
Any suggestions?