[[sitrico]]

Gracias a los dos, al final funcionó con un método similar al de Roman, buscando con Google encontré el procedimiento:

Código Delphi [-]
procedure PostKeyEx32(key: Word; const shift: TShiftState; specialkey: Boolean);
{************************************************************
* Procedure PostKeyEx32
*
* Parameters:
*  key    : virtual keycode of the key to send. For printable
*           keys this is simply the ANSI code (Ord(character)).
*  shift  : state of the modifier keys. This is a set, so you
*           can set several of these keys (shift, control, alt,
*           mouse buttons) in tandem. The TShiftState type is
*           declared in the Classes Unit.
*  specialkey: normally this should be False. Set it to True to
*           specify a key on the numeric keypad, for example.
* Description:
*  Uses keybd_event to manufacture a series of key events matching
*  the passed parameters. The events go to the control with focus.
*  Note that for characters key is always the upper-case version of
*  the character. Sending without any modifier keys will result in
*  a lower-case character, sending it with [ssShift] will result
*  in an upper-case character!
// Code by P. Below
************************************************************}
type
  TShiftKeyInfo = record
    shift: Byte;
    vkey: Byte;
  end;
  byteset = set of 0..7;
const
  shiftkeys: array [1..3] of TShiftKeyInfo =
    ((shift: Ord(ssCtrl); vkey: VK_CONTROL),
    (shift: Ord(ssShift); vkey: VK_SHIFT),
    (shift: Ord(ssAlt); vkey: VK_MENU));
var
  flag: DWORD;
  bShift: ByteSet absolute shift;
  i: Integer;
begin
  for i := 1 to 3 do
  begin
    if shiftkeys[i].shift in bShift then
      keybd_event(shiftkeys[i].vkey, MapVirtualKey(shiftkeys[i].vkey, 0), 0, 0);
  end; { For }
  if specialkey then
    flag := KEYEVENTF_EXTENDEDKEY
  else
    flag := 0;

  keybd_event(key, MapvirtualKey(key, 0), flag, 0);
  flag := flag or KEYEVENTF_KEYUP;
  keybd_event(key, MapvirtualKey(key, 0), flag, 0);

  for i := 3 downto 1 do
  begin
    if shiftkeys[i].shift in bShift then
      keybd_event(shiftkeys[i].vkey, MapVirtualKey(shiftkeys[i].vkey, 0),
        KEYEVENTF_KEYUP, 0);
  end; { For }
end; { PostKeyEx32 }

Que simula la pulsación de cualquier tecla. Al final Quedo Asi:

Código Delphi [-]
If (dbAsi.State <> dsBrowse) And Not(ssShift in Shift) Then
   Begin
   If (Key = VK_DOWN) Then
      Key := VK_TAB;  // Down As TAB
   If (Key = VK_UP) Then
      Begin  // UP As Shift+Tab
      PostKeyEx32(Vk_Tab,[ssShift],False);
      Key := 0;
      End;

Sobre:

Empezado por Roman

¿Usar las teclas de dirección vertical para movimiento horizontal?

"El cliente siempre tiene la razón"

Gracias nuevamente