If you go to your local hobby shop, Tamiya makes a fine point paint pen. It's basically a felt tip pen but it has paint in it instead of ink. When I had the patience to build model cars, I would use it to paint the emblems on the car bodies. So I think it would be perfect for you. Testors makes one also, but the tip is a little fatter, almost like a magic marker. I think either one will work. I used the Testors one for the dash on my car years ago.
