Surprising simple:

public delegate IEnumerator BookSelectEventHandler();
public static event BookSelectEventHandler BookSelect;
public void OnBookSelect()
{
    BookSelectEventHandler bookSelect = BookSelect;
    if (bookSelect != null)
        StartCoroutine(bookSelect());
}

And you can only add functions with the return type of IEnumerator:

• Only the last event handler to be added will be called -- Luiz
  
• I only use one, so it works for me

And this is how you would add the function to the event:

BookSelect += RenderWholeBook;

Updated my answer. Everything works perfectly.

I'm not sure what your intentions are, but you can't start a directly coroutine from a static method since StartCoroutine is a member method from MonoBehaviour. Another problem is that the event handlers must be a coroutine, so they must return IEnumerator.

public delegate IEnumerator BookSelectEventHandler();
public static event BookSelectEventHandler BookSelect;
public void OnBookSelect()
{
    if (BookSelect != null)
        StartCoroutine(BookSelect());
}

static IEnumerator RenderWholeBook()
{
                //snap
    yield return null;  //return next frame
                //change text
    yield return null;  //return next frame
                //snap next page
    yield return null;  //return next frame
                //turn off
    yield break;
}

(...)

BookSelect += RenderWholeBook;

However there's a problem: only the last handler is called.

Your delegate needs to return an IEnumerator, as well as BookSelect's function, which is probably assigned from elsewhere. Then, you call StartCoroutine(bookSelect());