When you see the MBL Duo show up in finder under shared - it is connecting via AFP.
To connect to it via SMB, you select “Connect to Server” under the “Go” options in Finder (this is on Lion).
You then can connect to the Duo using something like this:
smb://MyBookLiveDuo
if you don’t have users setup, just select Guest.
Backups - well you can’t use time machine over SMB, so it would have to be a Mac flavored Backup program.
