Just to make sure I understand you are not talking about the tool to actually press the ball joint out of the a-arm, is that correct?

You are talking about just separating the top of the ball joint from the knuckle, right? If so then that would be the same as separating tie rod end which I do with an pnematic fork mount in my air hammer. Will separating the ball joint with a fork and hammer ruin the boot?

I've just never done ball joints so I want to be clear.