Random function in Content Query Web Part

I've customised a CQWP by editing the .webpart file and changing the XSL in ItemStyle.xsl.

Now, I'd like to make the query random and I'd prefer to do it in CAML rather than XSL. Is there a property of the CQWP that makes this possible? I know there's no "random" property but could I change one of the many other properties to make some sort of pseudo-random query.

Thanks.

[407 byte] By [sondergaard] at [2008-1-1]