Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Random Seed
HP_SURFACEPOS_SEEDParameter: Object
HP_SURFACEPOS_OBJECTParameter: Type
HP_SURFACEPOS_TYPEParameter: Selection
HP_SURFACEPOS_SELECTIONParameter: Animation Time
HP_SURFACEPOS_ATIMEParameter: Position
HP_SURFACEPOS_OUT_POSITIONParameter: Alignment
HP_SURFACEPOS_OUT_ALIGNMENT