Get players used to not binding on the opposition drive, that way no maul is formed, and gives you 2 outcomes.

1. They get penalised if they drive more than a metre
2. as no maul is formed, the ball becomes the offside line as opposed to rear foot, that way players can just go straight round the back and tackle the ball carrier at rear, so long as its done from onside.

Just make sure that the ref is aware that you will be doing this at some lineouts.

Best if you do it in their 22 as there will be attacking options from it, but equally good in defending an attacking drive in your 22.

If you decide against the above, I drill my players to get 2 players to drive through the outside lifter and the jumper (once brought down). They then influence the roll and drive, which tends to move to touch. The opposition find it difficult to transfer the ball to the rear as it can become 'lost', and sometimes you can isolate the inside lifter and jumper and turn them.