Go to a local Paint Shop your going to want to buy Promotor
Pretty much what you want to do is sand the bumper all over and your going to spray the promotor on the ground effect the promotor bits in allowing the paint to stick to the urethane. Then you can put a prime over the bumper. then After that its just the normal. Hope this helps some. And Man I wish I could charge that much just to put my bumper into prime lol