I would take the camera, store it's position and angle, then turn it left 90 degrees, pitch it down 40 degrees (or therabouts), and move it forward by enough to put it in the bottom corner. Store that location, then put the camera back at it's previous location and orientation.
Then, to make something fly towards it, just point the object at that bottom left location, and move the object forward.
Might be a little messy, but it would avoid a lot of complicated math. One other option would be to make a cube, then offset the base limb (0) to -10,-6,0 - and position and rotate that object with the camera. Then you'd have a nice way to debug the corner position, and use the limb position to move objects towards. Hiding the cube once your happy with the corner location of course.
Health, Ammo, and bacon and eggs!
