I see from your posts that you are an experimentor and that you like to know as much about each treatment as you can. Good on you. I have been on the fasting forums here and they make it clear that a fast is only water. If you take anything else you are actually starving, not healing, even in tiny quantities.
Apparently the body preserves certain reserves when fasting and loses them when starving.
I read most of the books on urine many years ago (and Armstrong recently again) and only Armstrong made so much sense. He was definite and simple in his treatments however he did not reveal when to stop fasting.
I have heard of enemas many times using a variety of substances for helping to heal many things, but in regard to bowel movement I think it is unecessary and I am sorry I do not know anything about urine enemas.