That's what I do -- take mag supplements. I cannot stomach the Epsom, and can barely stomach the OO/GF mixture, so trying to do both is too hard on my stomach and kidneys, and I can't keep it down.
I follow Hulda Clark e's recipe, except take a mag supplement (500 mg) about 2 hours before I drink the OO/GF mixture. To clear out my system, I fast or do a liquid diet for at least the whole day before the flush, and usually a 1/2 day before that. Then, in the morning instead of the Epsom, I do about 2 quarts of coffee enemas, trying to retain them as long as I can (5 minutes is all I can do). It's not straight coffee, mind you, but coffee in water.
The coffee enemas really move out the junk! I just flushed last night and I got out tons of small green stones and a huge amount of chaff.