Add this element to the web.xml file:

<filter>
    <filter-name>StaticXSLT</filter-name>
    <filter-class>com.milowski.jaxp.XSLTFilter</filter-class>
    <init-param>
       <param-name>content-type</param-name>
       <param-value>application/xhtml+xml</param-value>
    </init-param>
    <init-param>
       <param-name>reload</param-name>
       <param-value>yes</param-value>
    </init-param>
    <init-param>
       <param-name>static-extensions</param-name>
       <param-value>xml</param-value>
    </init-param>
    <init-param>
       <param-name>extensions</param-name>
       <param-value>xml,jsp</param-value>
    </init-param>
    <init-param>
       <param-name>stylesheet</param-name>
       <param-value>site.xsl</param-value>
    </init-param>
</filter>