If you do intend to DIY, I would recommend taking off the bottom half of the bumper, not a huge job in itself. That will allow you to get the proper acces to it.
Make sure you paint the vertical supports for the center bar also.
I actually picked a full black gloss - personal preference, but you might prefer a semi gloss which may make it disappear more, if that is primary goal.
I'm confident Joe can give you excellent advice on prep, painting & finishing as our NSXPrime resident paint & body expert.
The one thing that helped make a first class job on mine was to have the base colors shot first, then clear coat on the entire bumper piece - this was fine since the whole bumper was being painted, but probably not an option for just the bar itself.
Fortunately its in an unobtrusive location so the edges won't be nearly so noticable - again, perhaps Joe can tell you how to minimize those.
[This message has been edited by D'Ecosse (edited 30 March 2003).]