This can either be done in standard tournament mode or during career where it is the second tournament on the calendar. Six matches have to be won in total. The tournament is leg format only where 11 legs are required to win up to the semi-finals and 16 legs are needed to win the final.
The main issue with this and all the tournament achievements is it has to be done in one sitting without turning off your console, without returning to main menu and without saving mid-match. Doing any of these glitches the achievement and you will have to do the whole tournament again.