Clear Coating Plastic NES Controllers Over Vinyl Decal. Help!

First of all, hey there! I need some help and I'm at a loss at this point. I'm a big nerd when it comes to video games and I've been itching to getting into console and controller modding. There's a man out there who does this by the name of CustomNESGuy and he does amazing work (please Google, I can't provide links yet).

Currently, I'm working on some controllers that I've painted nicely and I'm giving them plenty of time to cure. The problem is how the hell do I clear coat over the vinyl decal and get a mirrored finish like CustomNESGuy? This is my third attempt. The first was bad, the second came out mirrored, but I burned through it a bit. I also didn't allow the second controller to properly cure so there are indentations in it.

My question is do I simply use clear coat over the vinyl decals and spray on 8 or 9 layers of spray clear coat to bury the decal? Can I use polyurethane (which I've heard contradicting things about with vinyl and I am completely lost here)? I want to make sure that the protective coating is highly scratch resistant and hard. I also want a mirror finish. Can anyone here help me?