My "process" is simply setting up the bed in a way that, if I am using the knee-chest position the pillow I usually sleep with my head on is under my breasts, and my shoulders on the mattress just above the pillow
The other pillow is under my knees
The enema bag Is hung from the ceiling above the back half of the bed.
if I'm using a suppository as a pre-enema it goes in before I get into position
When it comes to retention the knee-chest position makes gravity your friend and your sphincter muscle can work WITH gravity instead of AGAINST it. That makes for better retention.
The pillow under the knees is just to protect the knees given that much of the body's weight is still back on the hips.
The one under my breasts, which have been described as "Ample" is simply to help distribute the weight off the breasts without having it on the neck or head.
The pillows hopefully will mean that when I;m 61 I won't have knees like my father's I have never had the warehouse and stockroom jobs that he had, and which clearly didn't help, especially since most didn't have motorized pallet jacks,.He never wore heels and a tight girdle all day! So it may come out the same in 30 years!
When I use the Simms position, one pillow goes under my head, the other under my hips, and another under my right knee, as much to keep me from rolling too far over as anything.
Any pre-enema goes in after I am in position
That whole business is covered with a large beach towel. a large bath towel is also right under where my rectum will be when in position.
Except for those odd situations where I finish up the session with a 4-qt enema, all the rest of the bags are sealed, HWB style bags. that way I have complete confidence that THERE IS NOTHING in that enema that I didn't put there! I can equalize temperature so much better with a closed bag!
My goal in EVERY enema is to take the full bag that I have chosen for myself, retain it 15 minutes, and expel it all in no more than 30 minutes after it started expelling.
98% of the time I can meet those goals and it typically takes me 3-4 rounds to get to a clear return. ( looks like pee out the butt) occasionally it takes more!