I don't see much that's helpful in the ACL manual
http://preview.tinyurl.com/y8nfazw --- how user-homedir-pathname behaves on windows
Beyond that, I'd suggest sending email to bugs@franz.com to ask for advice.
For that matter, Gary King was kinda deputized to speak for Allegro in this forum. Gary, are you there? Could you help Faré dig up information about where to dump special files in Windows with ACL?