I have had good luck with using a bottle with a hose stuck in it and starting with a little fluid in the bottle I connect the hose to the bleeder and make sure that the hose is into the brake fluid that I have in my container. When you pump the peddle you get air out and when you let off it has no choice, but to pull fluid back in instead of air! I run a restoration/fabrication business and I don't always have an extra hand (or foot) when I am ready to bleed brakes.
This method works well most of the time. Should work with the bleeder on the booster unit also. Sometimes you will need to bleed the master and then the booster and then the wheel cylinders!
Good luck!
