Good News!
I'm using MAME .139 on my cab and have modified it to fix the gear shift.

PM me your email and I'll send it to you late tonight.
It's just regular MAME though, so no user interface.
(hopefully you have a front-end set up to launch games)
EDIT: The original only had one switch, so adding a 2nd one isn't needed. It will work like the original.