Load the 1.05 firmware and browse to "http://<ip-address-of-DNS>/web/wfs_login.asp" where <ip-address-of-DNS> is of course the ip address of your DNS-323.
Please be aware that this was an undocumented and unsupported feature which has since been removed from later firmware versions - there was some talk of it being completed as an additional access method, but that never happened, and probably never will.
Be warned, downgrading firmware can lead to instability as bugs that were fixed in later firmware will be unpatched in the earlier versions and this particular feature is known to create security holes that could be a problem is your DNS-323 were exposed to public html access. If used on a secure LAN for access to files that are not considered highly sensitive, you should be fine.