US doesn't do much of anything in the way of special order custom work like that. About the most they'll do for a special order is fine tune the blade color to something non-standard if you email them about it and arrange it before making your purchase.
HOWEVER.... what you want done is pretty easy to do. I would recommend that you head down to your local craft or model store and pick up a small jar of gold model paint. It shouldn't cost you more than a couple bucks (literally lol), and get a small brush. You may want to keep a paper index card or something like that around to help you keep from going outside the grooves, but I've done just this sort of customization work on some of my own sabers, and some for friends, and it's VERY easy. Also, in my experience, the paint doesn't tend to wear off too easily when it's inside the grooves. Even if it does, you can just add a little clearcoat to seal it. You may want to lightly sand the grooves first to help the paint adhere. Be careful to sand ONLY the grooves, otherwise you'll be weathering the saber and scratching up that nice black finish. lol
Hope that's helpful!
