How many do you want other than you CANNOT do it, and it will NOT work. Steam radiators, especially one pipe systems MUST be above the main. Steam rises and condensage falls, and it has to drain backwards to the boiler. In the basement, the steam might get to the radiator, but the radiator would fill with condensation and stay there. That is why you see "flat panel" ceiling radiators along the basement ceiling of old buildings with one pipe steam systems.