In TG2 v2 you can navigate in the 3D Preview using the keyboard. Navigation is based around the arrow keys, with different modifier key combinations to do different things. You can see the key combinations by opening the Mouse and Key Settings window from the Help Menu. Expand the 3D Preview settings and then scroll down to the Navigation settings and expand that to see the movements and their keys.
The keys can be customised in the Customise Input Bindings window, which is opened from the Custom Bindings button in the Input Settings preferences panel.
I would have set up a WASD preset for this but it conflicted with a key which was already in use. If you prefer that you can customise it yourself.
You aren't able to "mouse look" as you would in a first person shooter type game, but this may be added in the future.
Another useful new key for the 3D Preview is the Return/Enter key. This key will copy the current view to the render camera.