The absolute minumum adventure level you can be in order to get this quest is currently level 55. You will however have some difficulties completing it at that level without some kind of help. You do not have to kill anything, but because of the very short range of the Dire Wolf Muzzle you must be able to survive standing very close to a Dire Wolf until the casting of the muzzle is finished.
Capture a dire wolf ( -444, 10, -252 ) /waypoint -444, 10, -252 in Loping Plains.
Place the Dire Wolf Muzzle you received in your charm slot, then use (activate) it on a Dire Wolf. You can find solo Dire Wolves northeast of the village, and heroic Dire Wolves west of the village.
Note: Dire Warg and Dire Ravager do not work for this quest.
Note: In spite of the quest text, you do not have to actually bring the Dire Wolf back to Wolfmaster Heinrich. Simply getting the muzzle on the animal seems to satisfy the quest. However, you do have to make it back to him without dying, because that will break the 'charm' that the muzzle casts on the wolf. If that happens, Heinrich will say something about you having some trouble, give you another muzzle and ask you to try again. Works well(29/5/2012)