I think you can accomplish this by setting the 'tab index' property of every focusable element on the main page to -1. This will cause the widget to be skipped in the tab order.
Have a look here for more info on this (3.2)
I think this might work:
In the closeMicroflow You could do a showpage of the overviewpage and set close pages to ‘all’ (if you have mx 9)
If you don't have mx9. You should use a close page action and then a show page of the overview page.