I have no idea how Ford did it. I have never painted chrome wheels but I have painted chrome parts with success. If there are significant blemishes they will need to be sanded with progressively finer paper ending with 320 grit. Wash and dry. Sand the entire surface starting with 320 ending with 600. Wash again, wipe with panel prep, and wipe with a tack cloth. Apply two medium coats of etching primer, allowing to dry between coats. Do the same with regular primer. Lightly sand with 600, wash, wipe, and tack. Apply the top coat of your choice following the directions on the can (ex. two medium and one wet coat). Don't use engine paint. It does not like lots of UV light. Chuck
PS If the chrome is flaking it is a whole other matter.