I think it was Telman that pointed out that the "flush" part of your flush (where the stones and toxins are pushed out of the liver and gallbladder) is over in 1/2 hour after you drink the OO (Olive-Oil) mixture. The salts in the morning are just to help clean the stuff out of your bowel. So as long as you keep it down for about an hour you can be pretty confident you haven't interfered with anything. It's just nasty stuff coming out both ends after that point. Unpleasant but not bad.
Aso, I've heard it's perfectly okay to drink water all afternoon; but not within 1/2 hour before or after the Epsom Salts and not after the last ES, that will help make you less likely to be naseous. But many people take a peppermint or bit of ginger after they drink the OO. And pretty much any juice with mixed with the ES is ok.