CustomPreference for user level can be set in UI and can override group level's setting

this idea has a support ticket: Case Number  01311109

I can only find places to set preference for certain group, not for single user.
According to
https://docs.tibco.com/pub/doc_remote/spotfire/7.6.0/doc/api/html/T_Spotfire_Dxp_Application_Extension_CustomPreference.htm
it says "Preferences properties can be applied to single users or to user groups."
I created a CustomPreference of PreferencePersistenceScope.Server as PreferencePersistenceScope and
PreferenceUsage.SingleUser as PreferenceUsage.
I do want to keep the preference to user level(although it can get value from group, but I need it to be able to override group level value).
currently there is NO UI to set SingleUser preferenece, they just don't show on preference tab in the admin menu of Spotfire Analyst.

It's more than just no UI, because I can always make a UI in our extension. 

Actually I want my preference to be set by customer's administrator and apply to a group of user. So I can't use the user level now. But I need the flexibility to override at user level AND STORE THAT VALUE FOR THAT ACCOUNT.