I've tried the Sgt Pepper's Ice Tea method on a few occasions, but it never seems to change the nature of the experience aside from a more minty stomach, which helps a little for the nausea. I've tried peppermint extract as well as cinnamon essential oil, with no effect aside from mintiness or spiciness in the stomach.
I usually let the simple mint/morning glory tea sit for about 12-24 hours. According to the people on the HerbMax forum, any sort of conversion would occur in an acidic and preferably alcoholic environment. I'm not sure I buy it, since it's all theoretical, but according to rumor it does change the experience for some people, so...
If I were you, I'd try the theoretical LSH conversion in water (and maybe alcohol) at a pH of 4 or less. Ascorbic acid, being an antioxidant too, would be a good choice.
Personally, I don't have any desire to change the morning glory experience, aside from cleaning up the quality of extraction. Just knocking out the stomach upset would help very much.
Happy experimenting, take good notes