It's not really face paint as much as it is just make up. I actually did it yesterday. He could just get a scar to get a feel for it. What they did was use like a makeup pencil and sponge with a little color on it. The scar takes just a few moments and if he's ok with that you could try the rest, or just call it done right there. Just the scar would look cool.
But even with no make up, there is a lot else! Before you even go in theygive you a pirate name. And they'll call him by that the whole time he's in there. Once the makeup portion was done they put a bandanna on me, gave me an eye patch, and "pierced" my ear with a hoop earring. The earring is just a clip on type thing, but it was a little uncomfortable at first.
Then,they call you over to a corner of the room where they give you a sword and sheath and tell you about your "Pirate Contract" with the captain (Basically tells the kiddies to not poke or hit people with their sword). Then they open the secret room where they keep the treasure (a necklace like all the other pirates wear) and you get you picture taken.
I think he'd enjoy it even without all the makeup.