DOM: Problem with loadXML(), createProcessingInstruction()

Apparently, loadXML() overwrites the existing structure of the document when called. The problem is that when I try to add a PI (namely a stylesheet), it adds it to the end of the document thus making so that the XML is not transformed by the client. To get around this, I thought I could just import my XML string into a DOMNode, but I do not see any method for that class analogous to the loadXML(). I looked at the possiblity of adding children to the document at specific positions (such that I could add the PI as the first child) but I do not see a DOMDocument method that allows it. appendChild() merely adds the child to the end of the document. Has anyone found a workaround for this; a workaround the fact that loadXML() completely replaces the existing document structure? thnx, Chris