Hi George, hopefully this will help.

1. Open up a terminal.
2. Type xinput list this will give you the name of your device. In my case, it is Evoluent VerticalMouse 4
3. To change the order of the buttons, run xinput set-button-map "Evoluent VerticalMouse 4" 0 3 0 4 5 6 7 0 2 1 2
4. I don't know what order you want your buttons in - so I suggest you read the blog post carefully to see which buttons are which.

Hope that help. Leave another comment if you want more info.