I think Invincible was suggesting in some post the use of ginger. You can prepare a cup boliled water ans one or two slices of ginger and drink it half an hour or 1 hour after the oil mix. I never had problems, my husband gets nauseous with olive oil and prefers to use sunflower oil. You should also pay attention to not drink any water 20 min before and after the oil mix.
Hope this helps, it mustn't be so great to vomit during the flush...