another option, which needs hardly any help from your enemies:
say 3 of you are at 1000 troops. attack one person with a stack of 200. now, likely, two of you will be at 800 troops, and one at 1000 troops. with a clear leader, you'll both attack the game-leader, bringing the 3 of you down to about 700 troops. make clear in the gamechat that this is what you're trying to do, do it a few more times, and at around 100 troops left per player(or more/less depending on the map and settings) take some risks, or see if someone else wants to take some risks. if you're lucky, it'll end. if it becomes a building game again, try again.
basically, so long as neither of you is stronger then the other two together, there's no real danger to losing yet, so feel free to waste some troops that way. also: teaming up against the 3rd guy might work, but be carefull they don't join up against you.