Add XSL element at runtime?

Hi,
I'm using XSLT to do a runtime transformation of underlying XML file. I selectively need to add sort tag to the XSL.

I've confirmed that I'm inserting in the right place however

xsl.createElement("xsl:sort");

does not seem to create the right kind of element (and the sort doesn't work). When I do a debug output the local-name() for all other elements does not have the xsl: prefix, but the sort one does - I believe this has something to do with namespaces etc. but is beyond my current knowledge. Googling isn't helping much.

Any pointers?

Thanks!