iFix 5.5 as a service and Ctrl+Alt+Del

The e-book states:

"You must assign the Enable Ctrl+Alt+Del application feature to the user that is logged in when iFIX is running as a service. Otherwise if a user logs out of the operating system while iFIX is running as a service, no one will be able to log back in to the operating system."

How do I enable this per Windows user?
Do I need to adjust FixUserPreferences.ini setting?

Thanks,
Justin