Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Exponential
COLORMAPPING_EXPONENTIAL
Parameter: HSV Model
COLORMAPPING_HSV
Parameter: Affect Background
COLORMAPPING_BACKGROUND
Parameter: Dark Multiplier
COLORMAPPING_DARKMULTIPLIER
Parameter: Bright Multiplier
COLORMAPPING_BRIGHTMULTIPLIER