Hi Dave,
What I've done for years is to paint the red line around the inside of the rim, then once that's dry carefully paint the rim black with a brush, paint marker or even a sharpie. I've done about 65 cars (x4 wheels) and have several sets of wheels made up for future projects and this method has always worked pretty well. It takes a fairly steady hand but you get the hang of it.
Just a couple things to note; If you look closely at full scale wheels, not all of them have red lines. Wheels that have been repainted a different color by the team won't have lines. Aero brand wheels used by many teams now have yellow lines. Basset brand have red lines. Circle brand wheels actually have thin red and blue lines and these are a little further in from the rim than the other brands. I've always just painted these with a red line because even on the real thing the blue line is fairly dark. As they always say - "Check your references".
Hope this helps. RcrX