Tomando la idea de AEFF y consejos de ixMike;
Código Delphi
[-]procedure TForm1.Button1Click(Sender: TObject);
var hWnd: Integer;
begin
hWnd := FindWindowEx(FindWindow(nil, 'Ejecutar'), 0, 'Button', 'Cancelar');
SendMessage(hWnd, WM_LBUTTONDOWN, 0, 0);
SendMessage(hWnd, WM_LBUTTONDOWN, 0, 0);
SendMessage(hWnd, WM_LBUTTONUP, 0, 0);
end;
Saludos