procedure TForm1.Button1Click(Sender: TObject);
var
  PackageModule: HModule;
  AClass: TPersistentClass;
begin
  PackageModule := LoadPackage('Package1.bpl');
  if PackageModule <> 0 then
  begin
    AClass := GetClass('TForm2');

    if AClass <> nil then
      with TComponentClass(AClass).Create(Application)
        as TCustomForm do
      begin
        ShowModal;
        Free;
      end;

    UnloadPackage(PackageModule);
  end;
end;

void __fastcall TForm1::Button47Click(TObject *Sender)
{
        unsigned PackageModule = LoadPackage("Package1.bpl");
        if( PackageModule != 0)
        {
                TPersistentClass AClass = GetClass("TForm1");

                ...
        }
}