Lee, are you saying you have a MFSW without paddles, or that you have a bog standard wheel and want to add MFSW with paddles?
If its the later then you will require MFSW, controller and slip ring. I would imagine if these parts were installed then you could enable the paddles to shift the box.
As for part numbers or coding I unfortunately have no idea, but the parts should be the same as manual cars that just want MFSW, as the paddles use the same control box slip ring etc.
HTH