Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Draw Mode
MDATA_POLYPEN_DRAWMODE
Parameter: Quad Strip Mode
MDATA_POLYPEN_QUADSTRIP
Parameter: Auto Weld
MDATA_POLYPEN_AUTOWELD
Parameter: Reproject Result
MDATA_POLYPEN_REPROJECT
Parameter: Create Coplanar Edge On Extrude
MDATA_POLYPEN_CREATEEDGEEXTRUED
Parameter: Create N-gons
MDATA_POLYPEN_CREATENGONS
Parameter: Create Semi Circle
MDATA_POLYPEN_HALFCIRCLE
Parameter: Arc Direction Max Angle
MDATA_POLYPEN_ARCANGLE
Parameter: Arc Subdivision
MDATA_POLYPEN_ARCSUBDIVISION
Parameter: Polygon Brush Radius
MDATA_POLYPEN_POLYPAINTSIZE
Parameter: Tweaking Mode
MDATA_POLYPEN_EXCLUSIVEMODE