I don't know if this works (I've never gotten dizzy from forward rolls), but here's a suggestion I came across:
Rolls are great for helping you learn to keep One-Point. That's because rolls make you dizzy, and keeping One-Point is the only way to stay stable when you're dizzy. . . . Tips: This exercise is meant to make you dizzy. If you keep One-Point, you will feel less dizzy. That's one of the great things about rolls - they give you feedback on whether you have the correct Ki state. When you don't have it, you feel dizzy. When you do have it, you feel stable."