If you are trying to match the paint on an existing bike for touch up or partial repaints, most automotive finish suppliers can scan the frame and come up with a very close match. Due to fading and color variations during production, this is probably closer than using the original paint code. Just feather it out properly and buff the entire finish to an even gloss. Might not be perfect, but only you will ever notice. I did this for a fork and touchup for a 1990s Trek and it's really difficult to see where the old and new finishes blend.