The reason I said JM presses is because it's a press and extension all in one. It's not a skull crusher with the bar, as it doesn't go behind your head. You don't bring the bar down all the way either, so you can limit that based on how your elbows feel. Use a close grip, let the elbows travel away from your body but still IN, and bring the bar down over your mouth. You're going to stop high, and press it back up. It's like a skull crusher but with the bar traveling in a straight line.
Ugh...did that make ANY sense?