Personally:
Clean them very thoroughly (this will help with application and later removal), then lay down a moderately thick primary coat of dip getting about 50% coverage, continue with 3-4 more even coats getting full coverage, let dry about 20 minutes in between each coat. You can mask if you want to but it would be in your favor to not mask the tire. You could however put some sort of bag over your rotors and calipers but overspray will just burn off here. After you finish spraying just peel the overspray off the tires. If you do choose to mask, remove the masking tape immediately after you finish spraying the final coat. This will give you the cleanest, sharpest lines.
If I were doing it I would mask off the rotors with bags but not mask anything else and peel [intentional] overspray off the tires. When I do it I'm going to peel the dip off the emblems on the hub caps to match my grill. Look on YouTube for DipYourCarcom (dipyourcar.com is their website). They have countless instructional videos that will prove to be very helpful.