Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Emulation
MGDISPLACER_EMULATION
Parameter: Strength
MGDISPLACER_DISPLACEMENT_STRENGTH
Parameter: Height
MGDISPLACER_DISPLACEMENT_HEIGHT
Parameter: Type
MGDISPLACER_DISPLACEMENTMODE
Parameter: Direction
MGDISPLACER_POLYNORMALMODE
Parameter: Process Normal Tag
MGDISPLACER_PROCESS_NORMALTAGS
Parameter: Legacy Mode
MGDISPLACER_LEGACY
Parameter: Camera Dependent
MGDISPLACER_REFRESH_CAMERA
Parameter: Backface Cull
MGDISPLACER_REFRESH_BACKFACECULL