Cat roll tacking is not done for the same reasons as monohull roll tacking.
As a cat turns in either a gybe or tack, the outside hull has to travel further. The idea of a roll tack or gybe is to get the outside hull out of the water a bit to cut down the drag on this hull.
The basic idea is to keep your weight on the more stationary hull[near the stern]. In light winds, the crew moves 1st in the tack and the helm moves 1st in the gybes.

Hope that this helps

Paul