In traditional mode -
Select create angled plane command.
Select the face you want the plane to be angled to.
Select an edge/plane that will be the base of the new plane (this defines the 'rotation axis')
You should see your new plane with a dot at the end of the rotation line, and by postitioning your mouse over one end or the other that will 'flip' the plane normal direction.
To re-orient or flip an existing plane click on the plane then 'Edit Definition'. At first it looks like you only get to change the angle, but if you select 'angled plane' again from the drop-down list you can re-define the plane from scratch.
I'm not sure about sync mode, perhaps someone that uses it could assist.
bc.
2.4GHz Core2 Quad, 4GB RAM,
Quadro FX4600.
Where would we be without sat-nav?