From the 11.20 beta instructions:
Using the Mouse in VR
You can turn on a 3D mouse cursor while using VR by checking the “Enable 3D Mouse Cursor” box in Settings > VR Hardware
I've had zero success with this, mostly because there is no "Settings/VR Hardware" section.
Using an Oculus Rift w touch controllers and 11.20vr1
I intend to use the mouse for those hard-to-reach places under the dashboard where the touch controllers go blind