A common issue seems to be adding javascript to CDATA and the browser throwing a javascript error. To ensure the javascript works use the following code when adding CDATA:

<?php
/**
 * Append Caracter Data to a node and check for a javascript node
 * 
 * @param DOMElement $appendToNode
 * @param string $text
 */
function appendCdata($appendToNode, $text) 
{
    if (strtolower($appendToNode->nodeName) == 'script') {  // Javascript hack
        $cm = $appendToNode->ownerDocument->createTextNode("\n//");
        $ct = $appendToNode->ownerDocument->createCDATASection("\n" . $text . "\n//");
        $appendToNode->appendChild($cm);
        $appendToNode->appendChild($ct);
    } else {  // Normal CDATA node
        $ct = $appendToNode->ownerDocument->createCDATASection($text);
        $appendToNode->appendChild($ct);
    }
}
?>
The result should be:

<script type="text/javascript">
//<![CDATA[
function someJsText() {
   document.write('Some js with <a href="#">HTML</a> content');
}
//]]></script>

Here's a function that will create a CDATA-section around a string coming from SimpleXML.

<?php
function sxml_cdata($path, $string){
  $dom = dom_import_simplexml($path);
  $cdata = $dom->ownerDocument->createCDATASection($string);
  $dom->appendChild($cdata);
}
?>

If you would like to refer to the documentation for the class of the returned object, see http://www.php.net/manual/en/class.domcharacterdata.php

Here's some code that takes an associative array and prints it asXML() but creates CDATA sections for each string

<?php
class SimpleXMLExtended extends SimpleXMLElement{ 
    public function addCData($string){ 
        $dom = dom_import_simplexml($this);
        $cdata = $dom->ownerDocument->createCDATASection($string);
        $dom->appendChild($cdata);
    } 
}
function assocArrayToXML($root_element_name,$ar){
    $xml = new SimpleXMLExtended("<?xml version=\"1.0\"?><{$root_element_name}></{$root_element_name}>");
    $f = create_function('$f,$c,$a','
            foreach($a as $k=>$v) {
                if(is_array($v)) {
                    if (!is_numeric($k))$ch=$c->addChild($k);
                    else $ch = $c->addChild(substr($c->getName(),0,-1));
                    $f($f,$ch,$v);
                } else {
                    if (is_numeric($v)){ $c->addChild($k, $v);
                    }else{$n = $c->addChild($k); $n->addCData($v);}
                }
            }');
    $f($f,$xml,$ar);
    return $xml->asXML();
} 

/* sample */
$result = array("title"=>"CDATA Sample");
$result['items'] = array();
$result['items'][] = array('title'=>'Some string', 'number' => 1);
$result['items'][] = array('title'=>'Some string', 'number' => 2);
$result['items'][] = array('title'=>'Some string', 'number' => 3);

echo assocArrayToXML('result',$result);
?>

The is_numeric check could be changed by a more elaborate regular expression to check if the string is actually xml unsafe but this worked for me.