Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Component Mode
O_BEVEL_MODE_COMPONENT_TYPE
Parameter: Add
O_BEVEL_RESTRICTION_ADD
Parameter: Remove
O_BEVEL_RESTRICTION_REMOVE
Parameter: Selection
O_BEVEL_RESTRICTION_START
Parameter: Use Angle
O_BEVEL_MODE_SELECTION_ANGLE_USE
Parameter: Angle Threshold
O_BEVEL_MODE_SELECTION_ANGLE_VAL
Parameter: Bevel Mode
O_BEVEL_MASTER_MODE
Parameter: Offset Mode
O_BEVEL_OFFSET_MODE
Parameter: Offset
O_BEVEL_RADIUS
Parameter: Subdivision
O_BEVEL_SUB
Parameter: Depth
O_BEVEL_DEPTH
Parameter: Depth
O_BEVEL_SHAPING_EXTR
Parameter: Limit
O_BEVEL_LIMIT
Parameter: Extrusion
O_BEVEL_EXTRUSION
Parameter: Max Angle
O_BEVEL_POLY_ANGLE
Parameter: Preserve Groups
O_BEVEL_GROUP
Parameter: Shape
O_BEVEL_SHAPING_MODE
Parameter: Tension
O_BEVEL_SHAPING_TENSION
Parameter: User Shape
O_BEVEL_SHAPING_SPLINE
Parameter: Profile Spline
O_BEVEL_SHAPING_SPLINE_LINK
Parameter: Profile Plane
O_BEVEL_SHAPING_SPLINE_PLANE
Parameter: Symmetry
O_BEVEL_SHAPING_SYMMETRY
Parameter: Constant Cross Section
O_BEVELL_SHAPING_CONSTANT
Parameter: Mitering
O_BEVEL_MITERING
Parameter: Ending
O_BEVEL_CORNER_ENDING
Parameter: Partial Rounding
O_BEVEL_PROUNDING_TYPE
Parameter: Corner N-gons
O_BEVEL_CORNER_NGON
Parameter: Rounding N-gons
O_BEVEL_ROUNDING_NGON
Parameter: Phong Break Rounding
O_BEVEL_SELECTION_PHONG_BREAK
Parameter: Phong Break Miters
O_BEVEL_SELECTION_PHONG_BREAK_M