The expansion comes with 8 role cards which replace the original ones: 1 Sheriff, 2 Deputy, 3 Outlaw and 2 Renegade.
To play with 8 players, deal all these roles face down as usual. Each of the 2 Renegades plays on his own, and wins only if he is the last player alive. So, if in the final stages of the game the Sheriff is confronted by 2 Renegades, and the Sheriff is killed first, the Outlaws win!