From what I've messed around with instant isn't handled well. It makes the textboxes LITERALLY instant. As in they never show up. It breaks everything. Unless someone smarter than me can figure out a speed between "fast" and "instant", I think the answer is no, unfortunately.Say, is there a chance someone could make an Instant Text Speed cheat for the v1.1.1?
Even on Fast, the Text Speed is quite annoying. Using it in the older games like Emerald or HGSS spoiled me.