Update on this from the Commercial Director of S3V (Societe des Trois Vallees), Jean Pierre Lalanne.
On S3V Courchevel / La Tania: Every gondola (except the small one in the kindergarden of course) and every chairlift (detachable or not). Ski bikes are not allowed on drag lifts or the cable car (you can do the same runs using the Vizelle gondola instead).
On S3V Meribel-Mottaret: Only on the gondolas.
On Meribel-Alpina: Only on the gondolas but also with the approval of the lift operator.