It's really not a problem for him as he's used to them. The only thing I can say is that any child should eat very light, just like an adult. I don't use epsoms, therefore, my son doesn't either. Just give your child 1/4 cup of oil, plus 1/4-1/2 cup of juice (lemon or grapefruit) at night. When they wake up, have them take half a bottle of magnesium citrate. You can buy that at the grocery story in the laxatives section, and it doesn't taste that bad.

Epsom Salts are pretty hard on the kidneys; I wouldn't recommend them to children at all.

It's not a hard process. The hardest part for my son is eating nothing but fruit, veggies, and some toast in the morning with jam on it. Just be sure to stop eating at 2-3 p.m.; take water until 6 or so, then have an empty stomach for a good while before taking the oil mixture right before bed.