Can I take the red, green and blue channels from different cameras and combine them? (for an anaglyph)

I want to use two cameras and take the green and blue channel from the left eye, and the red channel from the right eye (think I've got that the right way round), and then make up the final output image from those three selected channels. Very easy effect to implement in Photoshop. Is there a way to do that in Unity in real time? Maybe some kind of post render full screen effect?