Trim paint

I have a '68 RS that's in great shape, but I'm starting to work on some little details to make it even better. I recently order four new side marker frames (the highest quality set offered) only to find that the black accent groove was not painted. Does any one have some suggestions on how to paint the small grooves in the chrome such as this?

Is prep required? Primer? Do you attempt to mask or try to remove the overspray using a compound? I know this isn't the first piece I want to replace that will have this problem, so I want to start off right?