UMI.CMS: How can I override the umiHierarchyElement->updateSiteMap method?

Question

CMS

You need to implement custom sitemap generation functionality. It would be ideal to override the updateSiteMap method of the hierarchy element class, but judging by the documentation, this is not possible.
The only option that I see is to make my own module for generating a sitemap, which will subscribe to element changes and write data to my plate, but I would like to somehow override the basic functionality.