Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Geometry
FBXIMPORT_GEOMETRYParameter: Curves
FBXIMPORT_CURVESParameter: Cameras
FBXIMPORT_CAMERASParameter: Lights
FBXIMPORT_LIGHTSParameter: Instances
FBXIMPORT_INSTANCESParameter: Markers
FBXIMPORT_MARKERSParameter: Subdivision Surface
FBXIMPORT_SDSParameter: Deformation
FBXIMPORT_ACTIVATE_JOINTSParameter: Normals
FBXIMPORT_NORMALSParameter: Vertex Colors
FBXIMPORT_COLORSParameter: Grayscale to Vertex Maps
FBXIMPORT_COLORS_AS_VERTEX_MAPSParameter: Up Axis
FBXIMPORT_UP_AXISParameter: Flip Z Axis
FBXIMPORT_FLIP_Z_AXISParameter: Tracks
FBXIMPORT_TRACKSParameter: Clean Tracks
FBXIMPORT_CLEAN_TRACKSParameter: Vertex Cache to PLA
FBXIMPORT_VERTEXCACHE_TO_PLAParameter: Poses
FBXIMPORT_SHAPESParameter: Materials
FBXIMPORT_MATERIALSParameter: Substances
FBXIMPORT_SUBSTANCESParameter: Single Material Selection Sets
FBXIMPORT_SINGLE_MAT_SELECTIONTAGS