[ecfisa]

Hola.

¿ Y no te serviría desactivar el evento MouseWheel ?

Código Delphi [-]
...
  private
    procedure MouseEvent(var Msg: TMsg; var Handled: Boolean);
  end;
...

implementation

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

procedure TForm1.MouseEvent(var Msg: TMsg; var Handled: Boolean);
begin
  if Msg.Message =  WM_MOUSEWHEEL then
   Handled:= True;
end;
...

Saludos.