I have not tried shipping build, but with development build you can set these settings in GameUserSettings.ini
like so:
[ScalabilityGroups]
sg.ResolutionQuality=80
sg.ViewDistanceQuality=1
sg.AntiAliasingQuality=2
sg.ShadowQuality=0
sg.PostProcessQuality=2
sg.TextureQuality=2
sg.EffectsQuality=2