Just practice Hitchcock zooms over and over again and you should have no problem following focus after a while... you may need an extra hand to do this depending on your lens, but fun non the less.
Huh? No offense, that's horrible advice. Just learn to focus. Basics first, then gradually ramp up the complexity. Hitchcock zoom is an extremely specialized move that you'll maybe use once, if ever. Not only that but it requires a dolly, something I doubt the op has, or has ever used. It's also an extremely complex thing to pull off requiring a camera operator, focus puller, zoom puller, and dolly grip.
Or maybe you were just trolling and I'm too tired to tell. Or alternatively, you're referring to something that is in fact not actually the "hitchcock zoom"