I have gotten away from the Dupont series, especially the Chroma Series mainly because of the price, but maybe I can help ya.
What you need to use is Dupont's #222-S Adhesion Promoter. I believe it is. I've used it a lot with success. The only thing that I'm unsure about is the stuff has a very slight yellowish color and I'm not sure if it will tint the white though. I'm trying to recall the times I used it over any white and I don't recall it altering any of the colors. You just have to lay it on thin, so I doubt there's enough there to alter anything. To be safe and if you have any left over paint, try it out on some junk metal laying around.
I've heard a ton of agruments that you have to spray whatever your gonna spray over the adhesion promoter while it's still wet & that is doesn't matter as long as you spray with in the same day you laid down the adhesion promoter. I think it's real difficult to run to your other spray gun and start spraying before the adhesion prom. dries. It's dries in seconds.