Actually, 4E wouldn't be hard to do a bending system with at all. Most of the templates would become stances, and you'd replace bending checks with the more usual level-based effects. I was using the Book of Nine Swords to emulate firebending a while ago, and 4E shares much with that book. However, this specific system wouldn't work, no, and it's probably late in its life to start. In another year, after I have a grasp for 4E balance, I might try to begin a 4E version myself.