I don't think going from tele bindings to AT bindings is any different than switching out any other type of bindings. I doubt you can reuse the existing holes, so you'll probably need to redrill for the new mount. If you do it yourself, make sure your new holes are not too close to the old ones.
I think they sell some sort of plugs you can buy and epoxy in the holes, but I don't know if you can just use just epoxy alone. It seems like I remember someone telling me that the plugs where better because they mimicked the flex of the ski or some shit.
shouldn't be a big deal if you go to a shop.