the way we bleed power steering systems at the dealership is to pull a vacuum on the pump while the car is running. gets all the air out in a couple of minutes, works perferctly every time.
you can use a vacuum source on the engine, run a vac hose to the pump's cap, (there is usually a small hole in the cap )- you can hold the hose on the small hole in the cap and you will hear the pump load up when the vacuum is created in the system. all the air will be gone in a minute or so as soon as the pump quiets down