<p>I've discovered that cElementTree is about 30 times faster than <code>xml.dom.minidom</code> and I'm rewriting my XML encoding/decoding code. However, I need to output XML that contains CDATA sections and there doesn't seem to be a way to do that with ElementTree.</p>

<p>Can it be done?</p>

It's not possible AFAIK... which is a pity.  Basically, ElementTree modules assume that the reader is 100% XML compliant, so it shouldn't matter if they output a section as CDATA or some other format that generates the equivalent text.
See
this thread
on the Python mailing list for more info.  Basically, they recommend some kind of DOM-based XML library instead.