Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Show in Viewport
FEATHER_OBJECT_SHOW_EDITORParameter: Viewport LOD
FEATHER_OBJECT_EDITOR_LODParameter: Generate
FEATHER_OBJECT_GENERATEParameter: Reverse
FEATHER_OBJECT_REVERSEParameter: Segments
FEATHER_OBJECT_SEGMENTSParameter: Spacing
FEATHER_OBJECT_SPACINGParameter: Relative Size
FEATHER_OBJECT_RELATIVEParameter: Rachis Length
FEATHER_OBJECT_REFERENCEParameter: Rachis Radius
FEATHER_OBJECT_RACHIS_RADIUS_BASEParameter: Top
FEATHER_OBJECT_RACHIS_RADIUS_TOPParameter: Start
FEATHER_OBJECT_BARB_STARTParameter: End
FEATHER_OBJECT_BARB_ENDParameter: Barb Spacing
FEATHER_OBJECT_BARB_SPACINGParameter: Variation
FEATHER_OBJECT_BARB_SPACING_VARParameter: Barb Count
FEATHER_OBJECT_BARB_COUNTParameter: Barb Length
FEATHER_OBJECT_BARB_LENGTHParameter: Variation
FEATHER_OBJECT_BARB_LENGTH_VARParameter: Curve (Top)
FEATHER_OBJECT_BARB_Y_DISP_TParameter: Variation
FEATHER_OBJECT_BARB_Y_DISP_T_VARParameter: Curve (Base)
FEATHER_OBJECT_BARB_Y_DISPParameter: Variation
FEATHER_OBJECT_BARB_Y_DISP_VARParameter: Displace
FEATHER_OBJECT_BARB_Z_DISPParameter: Variation
FEATHER_OBJECT_BARB_Z_DISP_VARParameter: Rot Step
FEATHER_OBJECT_RACHIS_ROTATION_DELTAParameter: Variation
FEATHER_OBJECT_RACHIS_ROTATION_DELTA_VARParameter: Rotation
FEATHER_OBJECT_RACHIS_ROTATIONParameter: Variation
FEATHER_OBJECT_RACHIS_ROTATION_VARParameter: Rachis Rot
FEATHER_OBJECT_BARB_ROTATION_Y_VARParameter: Barb Rot
FEATHER_OBJECT_BARB_ROTATION_Z_VARParameter: Gap
FEATHER_OBJECT_BARB_GAPSParameter: Variation
FEATHER_OBJECT_BARB_GAPS_VARParameter: Occurrence
FEATHER_OBJECT_BARB_GAPS_OCCURParameter: Left
FEATHER_OBJECT_RACHIS_LEFTParameter: Right
FEATHER_OBJECT_RACHIS_RIGHTParameter: Left
FEATHER_OBJECT_RACHIS_SECTION_LEFTParameter: Right
FEATHER_OBJECT_RACHIS_SECTION_RIGHTParameter: Left
FEATHER_OBJECT_RACHIS_CURVE_LEFTParameter: Right
FEATHER_OBJECT_RACHIS_CURVE_RIGHT