How, exactly, does one do quest turn-ins to KOS NPCs?

[Ravager]

A Troll Warrior can't do it without help. One sure fire method, as long as being indifferent works, is to have someone lull/harmony the mob you're turning into then you open the trade box with that mob and while the trade box is open, but before you hit trade, that person casts invis on you. Once invis then hit trade. For things like faction quests though, it'll be very tedious. Wolf form is your best bet for those if it's good enough for the hand in.