I believe that he is referring to the side-to-side rocking motion of some mouse wheels, a different switch from the down-up wheel press, intended, I suppose, for horizontal scrolling on wide columns. There doesn't seem to be a way to map the panning function to that sideways rocker switch.

Google Sketchup isn't bad. It's just not as integrated as it could be. The only time that I used it was when I needed to make custom object for use with Unreal engine. Let's just say I was frustrating. The scale was always off and the properties of the object had to be re-entered in UDK. Was way way easier to use a decent 3D modelling program although you are totally right about how easy it is to use Sketchup.

The Orbit tool is used heavily when creating and editing models. SketchUp contains a few mouse enhancements and modifier keys to allow easy access to the Orbit tool.