Wanted: Weapons of Fate

You don't have to actually shoot 3 people during the eQM, just have 3 people die. You can do this much easier by shooting mines or gas bottles during eQM.

There's a great spot for it on the 4th floor of the bell tower. There's 3 or 4 enemies taking cover behind some crates and an orange gas bottle in front of them, just eQM accross and shoot the gas bottle to kill them all and get the achievement.

eQM is the slow-mo (using Y between cover) mode. You have limited time, ammo, and cursor movement while in eQM. So the key is to attempt this achievement when there is a tight cluster of enemies, but unlike "Glad I wasn't there" the enemies do not have to be physically close together. Both of these achievements are easiest in corridor and tunnel stages.

The shoot 3 guys method. ;)
Using the shoulder width of your character is a good guide for how close the 3 enemies should be. It's fine if they are running, as once you start the eQM all motion will stop.
- be in cover, with 2 bullets of adrenaline
- reload your weapon (I recommend the pistols for precision)
- try to line up your cursor near the center of the enemy cluster
- start the eQM
- try to fire no more than 2 shots at the heads of all 3 enemies, you will definitely have time for 6 shots, and maybe more
- the reticule will turn from red to grey if your target dies, but don't wait for it before moving on to the next target!
- if you have time left, sweep back to see if the reticule turns red and keep shooting

I did as follows. Chapter 9, low difficulty, boss. Right at the start waiting until the boss leaves and his henchmen appear. Melee kills whoever comes to you. Then, very importantly, you cover the right side and wait to be grouped. Use the gun and as is so pussy will give you more time to "bullet time" from one column to another. Practice several times and watch out.