If you already have something set up for getting the textures into UE4, you could set up a material to render to the screen UVs, and switch between the textures per eye using a custom node with the code return ResolvedView.StereoPassIndex; to get the current one.
I’m not sure what the most efficient way to render the material is, but you could attach it to a plane in front of the camera, or render it as post process effect.
