On that spinner, there is a jumper on on the encoding board that allows you to switch from X-axis to Y-axis. (Optional)
For suggestions on how to configure for multi-mouse, that depends on which flavor of MAME you're running. (basic command line MAME, MAME32, MAMEUIFX . . .)
The Graphic User Interface (GUI) versions usually have a checkbox in one of the configuration menu windows.
For non-GUI versions, you can open the mame.ini file and change multi-mouse from "0" to "1", save, and exit.
After that, map the desired spinner to the desired player default in MAME and you'll be playing Warlords in no time.

Scott