RAGE

In the story related job, "Liberate Captain Marshall," you will be sent to the Authority Prison. This is also right after your discovery of Mind Controlled Darts which are used with your Striker Crossbow. Later in the level there will be Authority Enforcers patrolling below you. Surrounded by them are mutants in prison cells. To your left is a power switch. Power off the switch and the mutants swarm to the two patrolling enforcers. Shoot a mind controlled dart into one of the two enforcers and quickly detonate. You will kill the two enforcers among with all the mutants.

*Update* 02/03/2012
-You can also obtain this achievement in Co-op mode as well. Thank you RaajTM for this input.

- If you happen to miss this achievement using the above strategy you can always go and replay "Bash TV" which is the video I used below uploaded by PowerPyx.

You can buy poison for more Mind Control Arrows as soon as you reach Subway Town (Disc 2). Thanks to z RagnaroK z for this info.

I found the wording on this achievement a bit misleading. You only need to kill 3 enemies total with the mind control dart explosion, including the enemy that explodes not 4 like I read it. (Confirmed)

The easiest place I found to accomplished this was in the Mutant Bash TV arena Round 1. Simply let 3 mutants crowd you, peg one with a mind control dart then keep hitting A so he explodes before the attacking mutants finish you off. Pop achievement. There is a chance the explosion will kill you too so make sure your defib is fully charged.

Wait to be attacked and surrounded by a group of enemies. Have your bow already out. Run backwards while firing into one of the enemies. He will explode without your view going into 'control' mode, killing the other enemies standing next to you/him. I got mine during the start of the mission "Blue Line Station", but anywhere your surrounded by enemies will work. I believe I took heavy damage from the blast, but I lived.

For those of you who want to get this in normal game play! I missed the opportunity to get this in "Liberate Captain Marshall" mission but found another spot were you could do it without enemies rushing you and getting hurt or missing the chance because of lack of enemies.
(make sure you have lock grinders, plenty of ammo, plenty of advanced wing sticks, plenty of mind control bolts, and a few advanced sentry turrets!)

In the mission "Power Struggle" when you get to the room were you have to use a lock grinder to get in the small room to avoid the moving ceiling blades, from the room kill the guys at the end of it waiting for you with mind control bolts or electric bolts for speed and so you don't use too much ammo or any of your gadgets.
Once they are gone you go through a few rooms and up stairs before you engage any other hostiles. (save at this point) Through the doorway on the left at the top of the stairs you will hear and see a guy with his back to you walking away, quickly wing stick him run down and there is a guy just to the right behind a pipe who you wing stick also. Now run to the right and there is a little walkway, bridge, gantry, whatever you want to call it!
Put a advanced sentry turret at the far end of it nearer the on coming enemies who you can now see running from the far left to your position, doing this gives them less cover and they just run into your turrets path and are mowed down and give your turret cover with advanced wing sticks! There will then be a slight pause were the enemies are holding back around the corner on the left, your turret still should be firing on them helping to pin them down. Advance and equip your bow with mind control bolts and there are three enemies taking cover, two on the left of a structure in the middle of the walkway and one on the right. Go for the guy taking cover behind the structure in the middle, when he's controlled make sure you have a similar gap between the two other guys and explode him and you should pop the achievement! More enemies come if you only kill a couple of them so another chance, but only took me a couple of tries from my save point to get it!

Hope this helps someone out! Sorry about the long description, don't have the gear to do a video or I would have made one!