uses
  IniFiles;

procedure TForm1.Button1Click(Sender: TObject);
var
  WinIni: TIniFile;
  WinIniFileName: array [0..MAX_PATH] of char;
  s: array [0..64] of char;
begin
  GetWindowsDirectory(WinIniFileName, sizeof(WinIniFileName));
  StrCat(WinIniFileName, '\win.ini');
  WinIni := TIniFile.Create(WinIniFileName);
  try
    WinIni.WriteString('windows','device', 'HP LaserJet Series II,HPPCL,LPT1:');
  finally
    WinIni.Free;
  end;
  StrCopy(S, 'windows');
  SendMessage(HWND_BROADCAST, WM_WININICHANGE, 0, LongInt(@S));
end;