I've only done this once but it turned out great, no need to primer first. I think I used Krylon. Whatever brand you use follow the directions on the can carefully. After painting you need to heat the covers to get the krinkle finish to appear. I just put mine in the oven but made sure my wife was going to be gone for a few hours first.
IIRC I just painted the entire covers, heated them, then carefully removed the paint from the fins and letters using solvent and/or fine steel wool. It's been quite a while since I did this.