I actually did this in hide & sneak. Complete that or raisin' a ruckus without alerting any enemies or using cheats. If cheats are on, or if enemies detected you, you'll have to start over. Achievement pops if the following:
1: The cheats are off.
2: You completed Raisin' a ruckus or hide & sneak without being detected (alerting any enemies).
To make things easier, I would recommend turning invisible and taking down enemies by pressing the R1 on the dualshock 3 controller or RB on the 360 controller.