On this web site under the Dr. Clark's gall bladder cleanses, it says that quote: "you can substitute 3 cups of water with 3 cups freshly pressed grapefruit juice or freshly pressed apple joice. That way you will not feel the unpleasant taste of Magnesium Sulphate."
My husband did the apple juice. I juiced organic apples in the Champion juicer and he had no trouble getting it down. He said it tasted like a slightly salty apple juice. He did think he couldn't get the second one down on the morning after, but decided he had to do this flush right, so he drank it. No problems, it stayed down.
Just an idea for you.
I wish you the best next time!
ps. Oh, and yes, he passed about 200 stones that day!