Here's an experiment I tried a week ago, using a blue Procion MX reactive dye, on a D Cyclone:

None of these were hot, I just brushed the dye on cold with various mixtures of dye, sodium carbonate, and thickener. The dye was left on the disc for 12 hours, but I suspect I could have removed it earlier with similar results.
The same dye didn't even touch Z and ESP plastics, though. The chemistry behind the process is a little too involved to explain in a DGR post, but it makes sense that D/DX plastic, with whatever crap they add in to make it cheaper and such, would accept the dye.
pd, I think further experimentation with different dyes is definitely a good idea... eventually we'll find the magic mixture and brilliant, permanent colors will be an achievable result. I just hope Scott Papa doesn't have me assassinated first...
We are not like those other golfers. We throw our clubs and keep our balls where they belong. -Ol' Bob