Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Direction
EXTRUDEOBJECT_DIRECTION
Parameter: Offset
EXTRUDEOBJECT_EXTRUSIONOFFSET
Parameter: Movement
EXTRUDEOBJECT_MOVE
Parameter: Subdivision
EXTRUDEOBJECT_SUB
Parameter: Isoparm Subdivision
EXTRUDEOBJECT_ISOPARM
Parameter: Reverse Normals
EXTRUDEOBJECT_FLIPNORMALS
Parameter: Hierarchical
EXTRUDEOBJECT_HIERARCHIC