I started by following the post here about using othAuth in 1.2 pre-beta but I was still getting some errors and ‘deprecated function’ warnings. What worked for me was not adding the line:
$this->othAuthRestrictions = Configure::read(‘Routing.admin’);
in the beforeFilter() function in app_controller.php as recommended in the post.
I then did some cleaning to eliminate the warnings. The final code I used is here.