Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

{ 
  This code allows you to replaces umlauts (i.e. 'д', 'ц', etc.) 
  with 'ae', 'oe', etc. while typing. 

  Mit diesem Code kann man Umlautzeichen (д, ц, ь usw.) durch 
  ae, oe usw. ersetzen. Dies geschieht applikationsweit, wдhrend der Eingabe. 
}

 procedure TForm1.AppOnMessage(var Msg: TMsg; var Handled: Boolean);
 type
   TReplacement = record
     chIn: Char;
     chOut: string[2]
   end;
   TReplacements = array [0..6] of TReplacement;
 const
   Replacements: TReplacements = ((chIn: 'д'; chOut: 'ae'),
     (chIn: 'ц'; chOut: 'oe'),
     (chIn: 'ь'; chOut: 'ue'),
     (chIn: 'Д'; chOut: 'Ae'),
     (chIn: 'Ц'; chOut: 'Oe'),
     (chIn: 'Ь'; chOut: 'Ue'),
     (chIn: 'Я'; chOut: 'ss'));
 var
   i: Integer;
   c: Char;
 begin
   Handled := False;
   if Msg.Message = WM_CHAR then
   begin
     if Chr(Msg.wParam) in ['д', 'ц', 'ь', 'Д', 'Ц', 'Ь', 'Я'] then
     begin
       for i := Low(Replacements) to High(Replacements) do
         if Chr(Msg.wParam) = Replacements[i].chIn then
         begin
           Msg.wParam := Ord(Replacements[i].chOut[1]);
           with Longrec(Msg.lParam) do
             Hi := (Hi and $FF00) or VKKeyScan(Replacements[i].chOut[2]);
           PostMessage(Msg.hwnd, WM_CHAR, Ord(Replacements[i].chOut[2]),
             Msg.wParam);
           with Longrec(Msg.lParam) do
             Hi := (Hi and $FF00) or VKKeyScan(Char(Msg.wParam));
           Break;
         end;
     end;
   end;
 end;

 procedure TForm1.FormCreate(Sender: TObject);
 begin
   Application.OnMessage := AppOnMessage;
 end;