Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Matrix Mode
GV_POINT_MODE
Parameter: Use Deformed Points
GV_POINT_USE_DEFORMED
Parameter: Point Index
GV_POINT_INPUT_POINT
Parameter: Point Position
GV_POINT_INPUT_POSITION
Parameter: Point Count
GV_POINT_OUTPUT_POINT
Parameter: Point Position
GV_POINT_OUTPUT_POSITION