I've been here. The problem is that some things changed between Zenoss 3 and Zenoss4. I modified the BatchDeviceDumper.py from a Zenoss 4 so that it works with Zenoss 3 (see the "JC" comments). You are welcome to a copy - no guarantees, as ever ;)
Sorry - the forum won't let me upload a Python file. Send me email and I'll send you a copy.