Actually, that old school trick works better than you'd think. Lacquer is a hot solvent that would dissolve the wax and pigment completely. It's not like sprinkling crayon bits on a finished car. The whole mix gets sprayed on and dries as one solid layer. Plenty of guys used stuff like that for custom colors back when options were limited. The key was grinding it to a fine powder first so it mixed in smooth.
Man, that's a total paint job nightmare waiting to happen. Imagine a kid's drawing melting into the clear coat on a hot day. You'd have a sticky, waxy mess sealed right into the finish. Good luck buffing that out without taking the whole layer off. It's basically a recipe for a permanent, colorful stain.