c := TCanvas.Create;
c.Handle := Your HDC...
try
  Bitmap.Width := ...;
  Bitmap.Height := ...;
  r := Rect(0, 0, Bitmap.Width, Bitmap.Height);
  Bitmap.Canvas.CopyRect(r, c, r);
finally
  c.Free;
end;

ImageEnVect1.AddNewObject;
ImageEnVect1.ObjKind[IEV_PREVIOUS_INSERTED_OBJECT] := iekBitmap;
ImageEnVect1.SetObjRect(IEV_PREVIOUS_INSERTED_OBJECT, Rect(10, 10, 100, 100));
ImageEnVect1.ObjSetTBitmap(IEV_PREVIOUS_INSERTED_OBJECT, Bitmap);