Short story, on a completely stock ubuntu, (and should work for anything) this will flip your scrolling:
- open a terminal
- run `echo "pointer = 1 2 3 5 4 6 7 8 9 10 11 12" >> ~/.Xmodmap`
- logout of your X windows session.
- log back in.
Up and down scroll are considered physical buttons 4 and 5, respectively. The "pointer = " statement above has 4 and 5 swapped. Simple as that.
Use `xmodmap -pp` to display your current button mappings, and `xmodmap -e "pointer = default"` to reset to normal. If you want to suss out where all of your buttons are, launch `xev` to see what events X is handling .. look for the ButtonPress event and note the "button" attribute.