First you get a AT4 out then go to a grenade luancher aim your AT4 at the floor just infront of the Grenade luancher nad fire as soon as you fire press the shift key when you press space bar after you should respawn back at the nade launcher instead of the spawn point.. This takes time and practise and don't shich weapons after you gto it right because you lose it then... and if you get killed you have to do it again...Have fun with this one...