Extensions in short hair?

I am currently involved in a production where my main character (male) needs to have shoulder-length hair. The issue that arrises is that his natural hair is only about 2 inches long. There is too much movement by the actor to use a wig, so I have to do extensions. Will it be possible to put extensions into his hair, or does anyone know of any other methods I can use?

My only issue with a wig is that the actor will be doing flips and sword-fighting maneuvers, and I'm terrified that the wig will fall right off his head.

Wow! Thank you Amanda... How would I go about getting shrinkies... To be perfectly honest, I've never even heard of them, and am unsure of what exactly they are, where to find them (is this something I would buy, and stylist would put in, or would a salon be able to do the whole process for me?). Any information you could give me would be greatly appreciated. Once again, Thank you for your reply.