How can I get the individual cameras for each eye in a GearVR app?

I need to create a mirror with actual stereo depth. In order to do this I need the positions of both the left eye and the right eye cameras in real time. Or the relative positions to the center camera, then I could figure them out.

After that I need to print different textures on each camera, so I actually need access to each camera, not just their position.

Is this even possible?