If Java is not working next best option would be to use the external FTP server function and setup an FTP Server on your laptop/PC and backup that way.
When a backup is initiated, the 3300 will do it's thing and then tar everything together ready to transfer to your PC. If it fails to transfer you can still FTP it off the 3300 I believe. It will be called Ipera3k.dba and is located in the /vmail/temp/db/archive directory, just rename the file to backup.tar (or whatever else you like with .tar) and that should be the same as a normal backup.
I have not tried this so use at your own risk