That sounds right.
There seem to be a few trains per day Aéroport CDG 2 TGV –> Lyon Part Dieu. You can purchase tickets at voyages-sncf.com (FR) or tgv-europe.com.
Admittedly, I don't know much about rail passes, but I would think that two one-way tickets like this would be more economically purchased singly than as part of a rail pass.
Peace.