Welcome aboard, bpjacobsen.

1. Does it work in Windows? Turning the spinner left/right should move the Windows cursor left/right.
2. If so, is mouse enabled (1) in mame.ini?
#
# CORE INPUT OPTIONS
#
coin_lockout 1
ctrlr
mouse 1 <------- enabled
joystick 1
lightgun 0
If you don't have a mame.ini file in either the "..\mame\" or "..\mame\ini\" folder, you can generate it using "mame -cc" . (create config)
Scott