The sigmoid colon is on the left side. That is where you want to lie. That is where all the the exchange of the elements in the coffee takes place. Doesn't really serve any purpose to lie on your right side. You don't want to drain it away from where it should be.
I almost never have any problems holding for 20 minutes, but at least try for 10 from the left side.
I bought a cheap stethescope off ebay and pass the time listening to all the sounds.
Never, never, never have I gotten stones from a coffee enema. I think it's more of a chemical release, moreso than anything else. However aside from that, is this.
I sometimes cleanse before a coffee enema, including Epsom Salts and salt water flush. Pretty clean, not much of anything else coming out. After the coffee and the initial expel, a follow-up enema will bring out a lot more solid stuff. So, even if you don't know how the liver may be affected, it certainly has a cleansing affect on the intestines.
But I also note, that if I continue a fast into the next day, with Epsom Salts , even more stuff appears.