IList lista = session.CreateCriteria(typeof(Keyword)).List(); 

                Keyword kw = new Keyword( "red" );
                kw.Id=1;
                lista.Add( kw );

                kw = new Keyword( "blue" );
                kw.Id=2;
                lista.Add( kw );



                KeySet  ks = new KeySet( "colors" );
		ks.Id=1;			
                ks.Keys = lista;