Sometimes a good position to receive an enema is if the receiver of an enema lies across the lap of the giver. I remember as a child receiving enemas in this manner from my mother.
I suspect that my mother used this position because she used a squeeze bulb syringe and would refill it four or five times during her procedure. I guess she prefered to have me lying down.
My mother would call me into the bathroom. She would have a basin full of soapy water with a bar of Ivory soap floating in it. She would have a bath towel accross her lap and would lift me across her knees. With her left elbow she would hold me down while using her left hand to spread my buttocks. Her right hand would insert the syringe. My mother made no fuss. She would insert the syringe, squeeze the bulb, pull it out again, and refill. She would continue until I was full. I guess I rather enjoyed the attention.
Although I have had many enemas since then and enjoyed every one of them, I would love to meet another woman who would take me face down over her lap and do it that way. I would probably be a funny sight but this would be a pleasant variation from the lying on your side or the knee to the chest position for receiving an enema.