I wrote a little Python script to automatically retrieve the configuration files from a bunch of ZyXEL DSLAMs. You can find it at http://pastebin.com/raw.php?i=vFpnhndJ.
The script takes an external file called dslams.csv. It serves as a list of all your DSLAMs that you want to backup the config from and uses a very simple format:
Note that the DSLAM names are declarative only and need not correspond with the DNS hostnames. Furthermore, you might use DNS hostnames instead of IP addresses.
You also need to edit the script and set the ZyXEL Web Configurator username and password in the dslamUser and dslamPass variables accordingly before you can use it.
Once the script runs, it will save DSLAM configs as