Overriding Magento's Google Sitemap: how to override Mage_Sitemap_Model_Resource_Catalog_Category?-Collection of common programming errors

I’m trying to override Magento’s functionality to create a sitemap.xml file (Catalog > Google Sitemap in the backend). The idea of my override is that not all product- and category-URLs should be included in the sitemap, I need the category-path of a product or category to determine whether to include it or not.

So this is what I did, I added this to my module’s config.xml:

...

    ...
    
        ...
        
            
                Company_Module_Model_Sitemap
            
        
        ...
    
    ...

...

The class Company_Module_Model_Sitemap is overridden well, but it turned out I also need to override the resource model to be able to achieve my goal, so I added the following to the config.xml file (between the models-tag):

    
        Company_Module_Model_Sitemap_Resource_Catalog_Category
    

Now it starts to go wrong.. It somehow won’t even load the backend grid anymore, navigating to the backend page of Google Sitemap yields the following error:

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'sitemap_id' in 'order clause'

Curently, the only content of the Company_Module_Model_Sitemap_Resource_Catalog_Category class is the following:

class Company_Module_Model_Sitemap_Resource_Catalog_Category
     extends Mage_Sitemap_Model_Resource_Catalog_Category { }

So finally, my question: how to correctly override the Mage_Sitemap_Model_Resource_Catalog_Category class in Magento?