MagicMouse and Trackpad Orbiting/Zoom Here is my set up: I'm running Blender 2.76 on a Macbook with an Magicmouse attached. I'm quite happy that in this version as opposed to older versions (this changed around 2.6ish) the two finger dragging on the trackpad acts more naturally (rotating instead of zooming) but unfortunately this messes up the magic mouse as well (scrolling is changed to rotating as opposed to zooming). This video illustrates a method to return this to the old way, but this removes the new trackpad behaviour.

Is there a way to have the trackpad behave the new way while having the magic mouse behave the old way at the same time?
This answer might be a bit late for you but may help other users.
I have found that ctrl + trackpad-scrolling or ctrl + magic-mouse-scrolling zooms.