How to override aggregator_block_view() in the aggregator module? Can anyone tell me how to override aggregator_block_view in the aggregator module?

I have a feed I need to alter the html for and at the moment aggregator just turns the output into an unordered list.

I tried altering it in hook_item_list() but there was nothing for me to lock onto to identify the list as coming from the aggregator module.
IF you want to alter the block view you can try hook_block_view_alter

Refer to menu block alter example for an example 

http://api.drupal.org/api/drupal/modules%21menu%21menu.module/function/menu_block_view_alter/7

---UPDATE---

  function hook_aggregator_process($feed) {
      foreach ($feed-&gt;items as $item) {
        mymodule_save($item);
      }
    }


Check out the docs at http://api.drupal.org/api/drupal/modules%21aggregator%21aggregator.api.php/function/hook_aggregator_process/7

Also enable the aggregator settings at admin/config/services/aggregator/settings

----UPDATE-----

Also if you just want to override the item list then you should use themename_preprocess_aggregator_summary_items(&amp;$variables) and check for 'summary_list' this holds the items list. For more details refer to template_preprocess_aggregator_summary_items in the aggregator.pages.inc file.