Problem with string that contains XML-tags

Hi

I have a problem with a string that contains XML-tags.
I created a domdocument and want to import a string with serveral xml-tags
into the domdocument. But it does (obviously) not work because the < and >
are written encoded. I want to ask now if there is a way to import a
wellformed string into an existing domdocument without parsing the string
and creating domelemnts for each xml-tag found in it (because this would be
*very* complicated). I guess there might be a function like eval for the
xml-implementation.

I'm using PHP 5, and yes i looked at the manual (which is not very complete)
and i tried most functions i could get with get_class_methods($domdocument).

Thanks for your help.
mfg Chris