1)Drop any item where you stand, preferably the armor.
2)Drop any second item where you stand. Due to DoomRL engine, it will get moved into one of nearby unoccupied tiles, so with a little bit of luck, it will land to your left. This item must be a consumable, though. If it lands to the right, pick it up and drop it again over the armor.
3)Make one step SE.
4)Wait until formers start to come under your butchering hand.
Ah, see, this is what I tried. They meleed me to death. This method has the problem of an item not dropping to the left, and if you move back onto your armor, everyone in the room gets a shot at you. I might be mistaken, though. (That, and I had no more consumables).