RE: dynamic variable name/implementation question

> The usual solution is that instead of passing your stylesheet three
> parameters x, y, and z, you should pass it an XML document 
> 
> <param>
>   <x>1</x>
>   <y>2</y>
>   <z>3</z>
> </param>
> 
> and then you can navigate this document at will using XPath.

I'm having a bit of trouble doing this.
I'm running xalan as follows:
>java org.apache.xalan.xslt.Process -IN ext.xml -OUT ext_out.xml -XSL ext.xsl -PARAM parameters "<param-list><a>hello</a><b>goodbye</b></param-list>"

however, when I execute:
<xsl:value-of select="exsl:node-set($parameters)"/>
I would expect to get the values of all of the text nodes within, ie:
hellogoodbye

however, $parameters is resolved as a string:
&lt;param-list&gt;&lt;a&gt;hello&lt;/a&gt;&lt;b&gt;goodbye&lt;/b&gt;&lt;/param-list&gt;

Maybe I don't understand the purpose of node-set()...