I'm sure I've seen the opposite... joytomouse... let me look.
rampy
EDIT 1
"
JoyEmu and JoyEm are two TSR programs that, when installed, poll joystick port and mouse and stuff keyboard buffer simulating keypresses according to device movements; keys to be stuffed, autofire rates, joystick sensibility and read mode, mouse sensibility are only a few of the many settings that can be changed. "
If crazy cab takes keyboard input you could simulate it with a mouse.... hypothetically with this TSR, maybe... =P
EDIT 2
http://www.geocities.com/adi001/mouse.htm this guy did an electronic hack that maybe would work for you (might have to switch from joystick emulation mode to normal spinner mode or something when not playing crazy cab... )
good luck...
EDIT 3 never mind edit 2... it's not quite what you were looking to do... but there should be a way electronically of maybe rerouting/changing the signal from a mouse to a joystick port/driver/something/anything =P