Suppose you have the EPSG:3021 coordinate system definition, which in WKT presents the datum as:

  DATUM["Rikets_koordinatsystem_1990"​]

but, for better ESRI interoperability, the user prefers the name D_RT_1990

In C#

In Delphi

  var
    dat : TGIS_CSDatum ;
  begin
    dat := CSDatumList.ByEPSG(6124) ;
    CSDatumList.Fix( 6124, 'D_RT_1990', dat.Ellipsoid.EPSG, dat.Transform.EPSG ) ;
  end;