You have to take something to relax the bile ducts to release the stones or you will be one sick puppy.
You can use magnesium malate or just magnesium and apple juice. I agree that epson salts are very harsh.
I tried numerous times to do a Liver Flush and there was nothing. I read Hulda Clrk's book and she says you have to take Taurine to build up pressure in the bile ducts. So I did that on my last flush. I pooped gravel for a week. Not hundreds of stones, thousands of stones.
So I would recommend what Clark says. Take at least 8g of Taurine through out the prep day to build bile pressure.
I also found something quite accidentally. I love artichokes but eating them one day I could actually feel my liver in spasm. I looked this up and found that artichokes due just that. They cause the liver to try to flush itself. I haven't tried it yet but along with the lemon and olive oil I'm going to eat some artichokes. It will either kill me or cure me.