Not using Epsom Salt during a flush is dangerous if you have a big stone that is trying to come out and gets stuck in the bile duct. I agree that Epsom Salt is very harsh to the body but so is taking a large amount of olive oil and lemon juice. So if you're going to do something extreme you might just well do it right and take epsom salt.
I've done a lot of flushes and have perfected the Epsom Salt intake to a science. Dissolve a tablespoon ES in a few gulps of warm apple juice and drink it through a straw. Follow up with a glass of water. Keep sipping water throughout the day to make sure you have enough fluid in your body to have diarrhea later.
You can take two doses of ES in the evening or you can skip the first dose and only take it at 8pm. You can even experiment and take it closer to the oo/gfj, around 9pm. I've head great results with this modification. I also take just one dose in the morning because at that point the bare thought of ES makes me cringe.
Good luck with your next flush!