Must be an engineer.
The only one of these achievements that MUST be done on an enemy. First, level up to a level 10 and then use all your points on the AI Hacking power. Then you can hack any of the enemies you come across. You will know when an enemy is hacked cause it will attack other foes of yours and will indicate to you it is hacked instead of having an energy bar.
Just find a turret to use it on... Use it, hide, recharge, rinse and repeat. People have recommended the fight with Fist as a great time to do this with the two turrets in his office. Make a save just before this point, hack them both and reload the save. The hacks will go toward the achievement even though you didn't save your game after doing them.