Can't get TransformerHandlerImpl from XMLFilter with getContentHandler?

[Jason Harrop]

Hi
I'm using XMLFilters.  I'd like to set stylesheet parameters on the 
underlying transformer.

Here's a code snippet which shows how i'm trying to do it:
    XMLFilter myFilter = SAXTransformerFactory.newXMLFilter( 
myTemplatesObject);

    org.apache.xalan.transformer.TransformerHandlerImpl handler = 

(org.apache.xalan.transformer.TransformerHandlerImpl)myFilter.getContentHandler();
     if ( handler!=null) {
         Transformer transformer = handler.getTransformer();
         // set away to your heart's content
         transformer.setParameter("testString", new String("predictable 
contents..") );
     } else {
         log.error("Couldn't get transformer for XMLFilter object :( ");
     }

The problem is, the handler is always null.
Has anybody got something like this to work?
I'm using Xalan from cvs sources, built a few mins ago.
thanks
Jason