For this achievement first you must side with Geeda, the female Rodian, during the merchant feud on Nar Shadaa. After some dialogue exchanges between you, her and Oondar, she will say that she wants to establish trade routes between Nar Shadda, Dantooine and Onderon. To do so, you must complete the main story quest on Dantooine and Onderon (the quest involving the Jedi Masters) and then return to her after everything is settled in on both planets. Talk to her about establishing merchant routes on both planets and after that she will have the "HK Protocol Pacifist Package" on sale, buy it and then return to HK on the Ebon Hawk to install it. HK will start saying some pretty funny comments about it
but sadly you'll have to uninstall it
. After uninstalling the module the achievement will pop.
NOTE: It seems before the update you could void the achievement by asking HK to stop asking you if you want someone killed, this however is fixed by the update, since I could get the achievement even after telling HK to stop asking me that. So if you arent unlocking it be sure that your game is updated.