in the Dreambox, there is a section for the CAM, go there, then click on the Aston CAM; there you will get the menus of the Aston CAM; choose the adult section there.
It works, trust me.
Just be sure to get an Aston CAM that works with your recent Canal+ card. I don't believe an old v1.03 or v1.05 would work. You are safer with a more recent Aston CAM.