Do you mean accessing the event object from within the event box ?

The structure of the event div is as follows:

<div> <-- this is the main event div
  <div>
    e.InnerHTML
  </div>
</div>

If you render your code in BeforeEventRender event you can reach the event object using the following code:

e.InnerHTML += "<input type='button'" + 
  "onclick='dp.eventMenuClickCallBack(parentNode.parentNode.event, 'Delete');' +
  "value='Delete' />";

This code adds a button that calls a custom callback action (it executes EventMenuClick event on the server-side, passing "Delete" as e.Command value).