I'm transitioning from a trackpad to a magic mouse and the lack of pinch zoom is killing me. I tried installing both better touch tool and magicprefs and can't get either of their pinch to zoom functions to work, and even if I could, they don't seem like they'd be all that easy to do. What would be ideal is to be able to simply hold down a key and scroll up or down on the mouse to zoom in and out. Is there a way to implement this myself? If so, is there something about this method that I'm failing to consider? It seems so much better than any of the existing methods using the mouse alone which either contort your fingers or run the risk of accidentally running other gesture commands.