initial D is REAL!

So I'm thinking of the best way to flush ps fluid without a special tool. I'm talking about generally for any car. Most shops have the tool that sucks out some old fluid and adds new fluid in while the car is running. We had that when I worked at toyota. When I worked at an independent shop, we hardly did those jobs because my boss didn't want to buy that tool, which they said was like 5K or more. He was very picky about not letting air in the system as well as not letting the pump run dry. ANyone have a good method that people can do in their own garage?.