These are the steps that I did, it works very well and they are not chipping at all.
1. Remove the grill surrounds. To do this you must first open the hood, unscrew the alternator cooler on the front and take it out. Reach down in front of the car behind the grills and pop them out. Then separate the chrome surrounds from the black plastic grills.
2. Take paint thinner and wipe down the chrome plastic surrounds to get them good and clean. Don't be afraid to use some rubbing force, the paint thinner will not take the chrome off.
3 Spray the now clean surrounds with rustoleum gray primer. Let them sit for 15 minutes.
4. Lightly sand the primer using 400 grit sandpaper, this is a perfect grit and will make the primer nice and smooth.
5. Using rustoleum "Hard Hat" flat black spray paint, spray the primed surrounds.
6. Drying time is as follows: 30mph - 15 min 60mph - 10 min 90mph - 5 min. 120mph - 1- 5 minutes.
Will Gilbert '99 ///M3