Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Matrix Mode
GV_POLY_MODEParameter: Use Deformed Points
GV_POLY_USE_DEFORMEDParameter: Polygon Index
GV_POLY_INPUT_POLYParameter: Polygon Count
GV_POLY_OUTPUT_POLYParameter: Index Point 1
GV_POLY_OUTPUT_POINT1Parameter: Index Point 2
GV_POLY_OUTPUT_POINT2Parameter: Index Point 3
GV_POLY_OUTPUT_POINT3Parameter: Index Point 4
GV_POLY_OUTPUT_POINT4Parameter: Polygon Normal
GV_POLY_OUTPUT_NORMALParameter: Polygon Center
GV_POLY_OUTPUT_CENTER