HI Mac long time no see. Hope you are doing well. If you have a chance stop in at RetroFest tomorrow if you have some free time. The details are on the diecast shows and events sectionI remember that we looked into this. The factory couldn't mix the paint so it had to be purchased elsewhere and shipped to them. That, along with the high cost of the paint itself, prevented any JL car from wearing it.
Note that I can speak for Playing Mantis and RC2 through 2007 but don't know after that.
I believe that Action/Racing Collectibles used DuPont ChromaLusion paint on 1:64 and 1:24th-scale Jeff Gordon cars...maybe others.