Just fire ur forwards into the maul as soon as u see it starting to form. U have to get them in b4 the a.i. tho. From a lineout start hitting the bind button as soon as u catch the ball.

Also useful to hold the ball in the maul a sec or2 after the initial shove, cause u can sometimes pick up 6 or 7m with a 2nd push. Doesnt always happen on elite tho