The half-hour online event is a prelude to the cable network's forthcoming TV special about the film.
Producer Jon Landau will also appear on the webcast, which is to feature new footage from Cameron's 3D sci-fi epic.
MTV News managing editor Josh Horowitz will moderate the panel. The special will also stream on the Avatar Facebook fan page, where viewers will be able to submit questions to the filmmakers and stars.
The webcast is to take place on December 3 and the TV special will air on December 16.
Avatar opens in cinemas on December 18.