[dr. F.I.N.]

Можно глянуть исходник TResourceStream:

Код:

procedure TResourceStream.Initialize(Instance: THandle; Name, ResType: PChar);

  procedure Error;
  begin
    raise EResNotFound.CreateFmt(SResNotFound, [Name]);
  end;

begin
  HResInfo := FindResource(Instance, Name, ResType);
  if HResInfo = 0 then Error;
  HGlobal := LoadResource(Instance, HResInfo);
  if HGlobal = 0 then Error;
  SetPointer(LockResource(HGlobal), SizeOfResource(Instance, HResInfo));
end;

Очевидно, Вам интересна функция FindResource