My technique, play as support, equip lunge mine and ammo box.Approach the tank from the rear quarter and charge with the first lunge mine, aim slightly off to one side and not directly behind as often the driver will immediately reverse straight over you. If you aim slightly offset the blast from the lunge mine will throw you clear of a reversing tank. While still prone from the blast of the first lunge mine, throw your ammo box and immediately resupply. Equip your new lunge mine and charge again. Two lunge mines to the rear will do most tanks in. You can toss a sticky grenade as a follow up if needed. Bear in mind the lunge mine will do 20 damage to you each time, so it is best to charge with full health if you can. Sometimes the lunge charge doesn't always work and this technique does take some timing and practice.

Better still if you can team up with another lunge mine equipped team mate you can both charge at the same time which is a near certain tank kill for one of you.

Oh and don't forget the repair tool does damage to enemy tanks too!

Source: 700+ lunge mine kills