Don't do it - it won't work. Both methods will automatically return false, in order to prevent infinite recursion from unskillful implementation of the event handlers. I've added a note about this to the relevant sections of the docs.
Mind you, I'm not entirely clear on why you would want to do this in the first place. I asked my contact at Product Support Services for the scenario, but haven't heard back. If anyone can shed some light on what problem this is attempting to solve, I'm all ears.