A bit of an old question, but I'll provide some feed back,
If you've done a mysqldump of the database (or pgdump depending on the backend) you essentially have the catalog in it's full state. I believe that you can simply restore this database to a new server, and restore the old config files (these are not stored in the dump but rather in /etc/bareos). Also, make sure that the same user/password is used for the database user as specified in the bareos-dir.conf file, or else you will not be able to connect to the database. Depending on how your storage devices are setup you may need to mess around with the baroes-sd.conf file.
To answer the other question off the OP, you can use a volume without a catalog. It's a bit cumbersome, but is possible with the following:
http://www.bacula.org/5.0.x-manuals/en/utility/utility/Volume_Utility_Tools.html
For example:
List jobs on a volume: bls -j -V Full_1-1886 FileStorage1
List files on a volume: bls -V Full_1-1886 FileStorage1
Once you have found the file, or directory (Note wildcard characters are supported) you can extract the file:
bextract -i restoreFiles -V Full_2-1277 FileStorage2 /tmp/
Where:
- restoreFiles specifies a file separated with newlines that lists files/directories to restore
- /tmp/ is the destination of the restore