You have to use disruption weapons all the time or/and negotiate with workers and Ghost Gang members. Make sure to:
-First fight at the gates against the Ghost Gang: The trickiest part as you don't have access to disruption weapons here so, take cover and let security handle them. This fight is very buggy and took me 3 hours to complete it. At least one Ghost has to be knocked out in every turn otherwise there is a high possibility that the fight will freeze, forcing you to reload. This depends on the AI though only.lf you have high dmg companions like the honey badger or the Soviet bot, its better to dismiss/kill them.
-In the factory sublevel equip disruption rounds to the war bot after assembling it and side with Ladlow. Or you can keep lethal rounds and side with Crow which is a better choice. DI will trigger this choice.
-If you are using disruption weapons so far, Ghost Gang and Blue will avoid to fight you after a 5 Kiss Ass skill check, but you can still knock them out if you fail it.
Achievement unlocks after completing the main steeltown questline. Using lethal weapons against robots at the Factory sublevel and at the Spire is totally okay.