Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Source
FP_COLORMAPPER_SOURCE_MODEParameter: Lower
FP_COLORMAPPER_MINFLOATParameter: Upper
FP_COLORMAPPER_MAXFLOATParameter: Gradient
FP_COLORMAPPER_GRADIENTParameter: Repeat
FP_COLORMAPPER_REPEATParameter: Alpha Only
FP_COLORMAPPER_ALPHAONLYParameter: Field
FP_COLORMAPPER_FIELDLISTParameter: FP_COLORMAPPER_DRAW_DISTANCE
FP_COLORMAPPER_DRAW_DISTANCE