Editing header.phtml with an XML file

[PemCogesonole]

I'm working on a magento web site and I'm trying to do some changes on the header.I want to add 2 blocks (module) that I've made.Is there a way to add them without touching the \[code\]header.phtml\[/code\] by putting : \[code\] <?php echo $this->getChildHtml(' ') ?>\[/code\]Is there a way using the XML files ?