Adding additional user option

[g0rn]

I'm trying to add an additional user option. I've overridden _getFields method in XenForo_DataWriter_User, but I have to also add my field to the allowed settings list in XenForo_ControllerPublic_Account, method actionPreferencesSave(), $settings array. I currently have no idea how to do add an element to that array. Can anybody suggest a way better than saving only that one field in overridden method and then calling parent and let it save all the others?
Thanks.