Someone did that before?...don't know.
This mod helps to get a Cruis'n, Offroad Challenge, Rush Series, Sega Daytona etc. 4-gear cab shifter working with mame and others without extra software.
Problem is that one of the four assigned keys at the shifter is permanently "pressed". That gets your PC/PS/Raspberry mad.
Because there's no neutral position.
I filed a small notch between gear 1-2, that the stick can stay there. (see 1st picture). The complete shifter is turned that the spring force of the shifter goes to left side. I'm sure this can be similar done for other UP/Down or LOW/High 2 gear shifters.
Get an "N" and you have a neutral gear!