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