unity - How to set the camera projectionmatrix so that it's 4 rays always exactly hit the corners of a defined plane?

I have a camera, and I have a plane. The plane has 4 corner points. I need to find out how to change the projection-matrix of the camera so that the projection-rays of the camera always hit the corners of the plane.

The camera and the Plane are supposed to be movable rotateable (if possible) The Plane is also supposed to be scaleable.

Usage:

I am making a Stereo-3D-Game with Eyetracking where my 2 Eye-Vectors hit the exact same paralax-plane.

That paralax-plane is defined. So we have the Corner-positions of the Plane.