Yes, magnesium chloride has been found to be most helpful in cases of tetanus. Dr. Delbert discovered its effectiveness in infections a long time ago, and more recently Dr. Vergini has confirmed this fact.
While intravenous administration of magnesium chloride is the best and fastest way to get the mag chloride into the body, the next best is transdermal magnesium chloride. This will increase your magnesium levels faster than any other type of mag chloride (pills, liquid etc.) and won't cause the diarrhea that oral products will.
IMVA recommends using Ancient Minerals Magnesium Oil, available through LL's Magnetic Clay. You can purchase it here: http://www.magneticclay.com
Use it lavishly on your skin 1-2 x day and use it in baths (get the magnesium bath flakes for this, its cheaper)