The switches are double-pole switches, so one side of each switch disconnects when the other side connects, probably as a failsafe for the controller. (If it doesn't see the normally-closed circuit it ignores the normally-open.) The switches are fed in a single connector, so it's not like you could take the plugs and swap them.
But if you can cut and splice wires, there are two wire pairs that would have to be swapped. On the 2006 diagram I have, you would swap the orange/white with the green/red, and then swap the orange/black with the green/black.
In automotive sequential shifters, upshifts are a pull, downshifts are a push, which kinda matches the buttons, doncha think?