I think you'll have to trick your way around it with the layers rather than the light. Maybe duplicating with one to not receive lights and another to cast shadow only. Maybe using.. can't remember the right name now, when you turn on the adjustment layer switch on a light
Wow. thank you so much.
this is it.
Although i thought that there would be a much easier solution because lights can only beam light . and objects can only cast shadows and so on. But, there IS a solution. so thats good.