procedure TForm1.Button3Click(Sender: TObject);
var
  MyList: TStringList;
begin
  MyList := TStringList.Create;
  try
    with MyList do
    begin
      Add('SERVER NAME=IB_SERVER:/PATH/DATABASE.GDB');
      Add('USER NAME=MYNAME');
    end;
    Session1.AddAlias('NewIBAlias', 'INTRBASE', MyList);
  finally
    MyList.Free;
  end;
end;