Yes, to do this you will need the full path to the private folder - use the InternalPathFN function
This gives the path without the trailing '/'.
Put InternalPathFN into fpath
Once you have this path then your app can use HAC's file commands just as if the folder fpath were a standard folder.
By the way, there is also DatabasePathFN - this gives the path to the database folder inside the above mentioned private folder.