This suits the situation where you sided with Netwatch in the "I Walk The Line" mission, in which you can't easily find Voodoo hacker enemies after the mission.
This method DOES NOT require any intelligence level, you only require a large RAM OS to be bought in any doctors. Currently, in 1.06 the item stack bug still works for "copying" the €$4000 painting.
Fast travel to "Chapel" fast travel point and go upstairs, walk a little bit you will see several tents, turn left in the tent area and go to the end of the road you will see 3 enemies watching TV. They will drop the purple "Detonate Grenade" quick hack.
After that, find any places where 3 of the enemies stack together, don't try it in the police enemies, because normally police do not carry lethal grenades which you can't get the achievement. I suggest finding any voodoo cult gathering places because normally they have more than 5 enemies standing in the stack.
It may be possible to use the "Detonate Grenade" on the 3 enemies stacked in the 2nd screenshot because their position looks like stacking(As I got my achievement from voodoo cult gathering I can't verify this to be working)