Sorry about the late reply. I was in Singapore and Hong Kong for seminars, lost track of some things.
Medicine ball throw wall slam: stranding up, throwing the med ball from the chest in an horizontal push toward a wall in front of you. Of course you need a very solid wall Alternatives are doing the same throw but without a wall, in which case you will jog to pick up the ball between each rep. Or do the chest throw lying down on a bench, throwing the ball in the air.
Overhead/push press action medicine ball throw: Imagine doing a push press but with a medicine ball, and releasing the ball so that it will go as high as possible. Don't try to catch it, let it fall in the floor, and pick it up between reps.
Overhead throw: similar to above but without using any leg drive.