Guitars can be chrome plated because there are conductive paints which can be used, this is how the original chrome boys were done. There are copper based paints out there. I can't verify if this specific process as I know how to do it was how the JS
's were done originally, but in order to chrome wood, or plastics, first the wood is sealed, primed, and painted (usually black) and buffed to a perfect shine. Then a copper based paint is applied to the body, this also is buffed to perfection. Then the guitar must be typically brass or copper plated, then nickel, and then finally chrome goes on top of that. The problem with wood is that it moves, the plating does not, this is why they crack, and why you end up seeing the wood grain eventually.
The Alsa Mirrachrome does not look 95% chrome, I'd say 80% and that is being generous, it gives a nice polished steel color, but nothing like chrome. Alsa has a system called Chrome FX which looks deadly, but you pay for it big time. Their application system is around $8000.
Here is what the Chrome FX system looks like
Here is mirra chrome, nice, but far from chromey
I know some phenominal painters who've used the mirrachrome, even the people who do testing for Alsa, and it looks fantastic before clear, the clear dulls it down a lot though, it's nowhere near 95% after clear. You can see that in the pictures from Alsa's site.