Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Splitting
OBJIMPORTOPTIONS_SPLITBY
Parameter: Lines
OBJIMPORTOPTIONS_LINES
Parameter: UVs
OBJIMPORTOPTIONS_IMPORT_UVS
Parameter: Normals
OBJIMPORTOPTIONS_NORMALS
Parameter: Phong Angle
OBJIMPORTOPTIONS_PHONG_ANGLE_DEFAULT
Parameter: Vertex Colors
OBJIMPORTOPTIONS_VERTEX_COLOR
Parameter: Flip X Axis
OBJIMPORTOPTIONS_POINTTRANSFORM_FLIPX
Parameter: Swap X and Y Axes
OBJIMPORTOPTIONS_POINTTRANSFORM_SWAPXY
Parameter: Flip Y Axis
OBJIMPORTOPTIONS_POINTTRANSFORM_FLIPY
Parameter: Swap X and Z Axes
OBJIMPORTOPTIONS_POINTTRANSFORM_SWAPXZ
Parameter: Flip Z Axis
OBJIMPORTOPTIONS_POINTTRANSFORM_FLIPZ
Parameter: Swap Y and Z Axes
OBJIMPORTOPTIONS_POINTTRANSFORM_SWAPYZ
Parameter: Flip Faces
OBJIMPORTOPTIONS_FLIPFACES
Parameter: Material
OBJIMPORTOPTIONS_MATERIAL
Parameter: Default Material
OBJIMPORTOPTIONS_DEFAULTMATERIAL
Parameter: Material Mix Mode
OBJIMPORTOPTIONS_MATERIAL_MIXMODE
Parameter: Invert Transparency
OBJIMPORTOPTIONS_INVERT_TRANSPARENCY
Parameter: Sequence
OBJIMPORTOPTIONS_SEQUENCE_ANIMATION
Parameter: FPS
OBJIMPORTOPTIONS_SEQUENCE_FPS
Parameter: Frame Step
OBJIMPORTOPTIONS_SEQUENCE_FRAME_STEP
Parameter: Shared Material
OBJIMPORTOPTIONS_SEQUENCE_SHARED_MATERIAL
Parameter: PLA Interpolation
OBJIMPORTOPTIONS_SEQUENCE_PLA
Parameter: Script Console Reporting
OBJIMPORTOPTIONS_REPORT_SCRIPTCONSOLE
Parameter: Import as UTF-8
OBJIMPORTOPTIONS_ENCODING_UTF8