I'm trying to add the ACP Add User MOD. From what I can tell from the xml file it wants me to copy various files into the phpbb folders. Is this possible? I'm not sure how to access the actual phpbb files.
The phpbb files live in /usr/share/phpbb3 on the appliance.
You can use sftp to transfer files to your appliance.
Webmin also has a file manager you can use to transfer files.