You can create a virtual studio in Lightwave in two ways.
1 - For live use - you can create a scene that you will key your live camera feed over - however this will not allow for any shadows or reflections, and is really only practical in a single camera situation.
2 - In post production - you can shoot all of your footage recording it to tape, or straight to the VT hard drives, and then importing the footage into Lightwave so that it is an element in the scene. This will not work live, but can allow for reflections, shadows, etc.