Unfortunately, OpenOffice is bad to automate unless you like Java and the object model that Java tends to impose.

You can also use Python to drive OpenOffice (not that that's much better than Java, mind you . . . :). I don't recall where I found the sample code I based what I wrote (a converter which munged SXC XML files (which had been run through Template Toolkit) into Excel XLS files), but the Python page in the OO wiki may get you started.

Update: Aaah, found the links to more examples: http://udk.openoffice.org/python/python-bridge.html