You can display a wheel by pressing Ctrl-Shift-N on the keyboard or activate the Show SteeringWheels option from the SteeringWheels preferences.
Once you set the SteeringWheels to display, use the available navigation tools by either clicking over one of the wedges on the wheel or clicking and holding down the mouse button. Once the button is held down, drag over the Viewer window to reorient the current view. Releasing the button returns you to the SteeringWheel.