AFAIK, when you transform an XML document using XSLT, CDATA sections and regular text are parsed together as one text item. However, you can parse CDATA sections and regular text separately using the XmlDocument class. Given the above information, you can use the Add Extension Object feature of the XsltArgumentList to achieve your purpose. IMHO, the below code is a bit overkill but it does the job. By the way, your second CDATA section will be transformed as text as and not an HTML element. To create a HTML element, you have to create it dynamically or statically in the XSLT code.
using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::Xml;
using namespace System::Xml::XPath;
using namespace System::Xml::Xsl;
public ref class ParseCdata
{
public: