A joystick from a computer aracde game can be hooked up to your stickshift to allow you to honk your horn, wash your windows, pop your doors, change radio stations, dim your lights or a number of other neat things.
I am new to this group so I am not sure about how to do stuff on here so bear with me.
Find a joystick that has enough buttons to do what you want it to do, dis assemble the joystick, isolate the different switching circuits, solder new leads, route thru to a relay board, wrap the stickshift lever with blue painter's tape,bondo the shaft of the stickshift to one half of the joystick case, pull stickshift lever free and re do on the other joystick handle. The relay board allows the small circuit capacity of the joystick to operate higher circuit loads.
Joy sticks will handle 1 amp max load thru their contacts.