FTP over Explicit SSL is definitely supported in 1.06 and it works. When you turn on FTP it's immediately available but you have no control over it- can't turn on/off FTPES, can't specify PASV range, can't install your own SSL certificate (one is provided but I have unanswered questions about it, PM me if you get yours working).
I still doubt it will work over the internet though; let me know if you have success.
To test your 323, Fire up FileZilla, set up a new connection to your 323's IP address (or ddns name), set the server type to FTPES, login type normal, choose "Active" under transfer settings and connect.