add extra TableTools button after initialization?

Is it possible to add buttons after the DataTable and TableTools have been initialized and rendered in DOM? For example from another Javascript file loaded after the one doing the initialization?

I've tried accessing the tabletools and adding extra button using TableTools.fnGetInstance( 'datatable' ).s.buttonSet.push(extra);
- where 'extra' is a regular button definition object. Should this work? I cannot however this way get the tabletool to re-render so the extra button would show.

Any ideas?