Some tips... like paint/clearcoat you'll get longest durability if you prep beforehand. If you have any old clay, use that on the wheel. If you have clayed before, then more likely you'll also have polish. Use that after the clay.
Then grab some plastic grocery bags and use those to cover your break/caliper. Even though that part is not in the Meguiar's instructions, I only do that so that I don't have one less thing to worry about when spraying. I tossed on 3 very light coats.
If you screw up the Break Dust Barrier, apparently it comes right off using just rubbing alcohol. I have used it on polish bare aluminum wheels. I didn't like it. Perhaps my coat was too thick, but what impressed me was the coat survived different wheel cleaner and degreasers. The only way I got it completely off the aluminum wheel was to use a polish. I didn't try rubbing alcohol on it. I didn't know that was it's kryptonite at the time.