Based on my car:
S-Saves the memory position; hold down until you hear a beep.
M-recalls the memory position (i.e. moves the seat from wherever to wherever). If you don't have a position set probably nothing will happen.
C-Cancel auto exit feature.
The auto exit feature returns the seat to the fully upright position when the rear door is opened and the engine is running (or the ignition key is in the 'on' position). Should you not want this after you open the door hit C and the movement will stop.
There is a button on console of my car to return the seat to the fully upright position and lower the rear headrests, not sure if the 460 has this or not?
-J