done with an external method to upload the content of zip file in
skin folder.

    import zipfile
    from io import BytesIO

    def uploadZip(self):
      dest = self.getPortalObject().portal_skins.custom
      with zipfile.ZipFile(
          '/srv/slapgrid/slappart3/srv/project/erp5/ckeditor_4.19.1_4b98d281bc34.zip'
      ) as f:
        for m in f.namelist():
          current_dest = dest
          print(m)
          for part in m.split('/')[:-1]:
            if part not in current_dest.objectIds():
              current_dest.manage_addProduct['OFSP'].manage_addFolder(id=part)
            current_dest = current_dest[part]
          fname = m.split('/')[-1]
          if fname == '_translationstatus.txt':
            fname = 'translationstatus.txt'
          current_dest.manage_addProduct['OFSP'].manage_addFile(
            id=fname, file=BytesIO(f.read(m)))
      return repr(dest)