I am very curious about this as well! Someone made an Autohotkey script for Ableton Live on Windows that allows you to scroll in any direction anywhere that is scrollable by holding the middle click button on a mouse.
I can send it to anyone who uses Live and would like to try it- really changed the game for me, though I hear on Mac you can just sidescroll with fingers? That would be a nice bonus to not use a mouse at gigs.
Is there a way to set something up like this for Arena as well?