pass an entire XML doc as an XSL param?

I'm using MSXML 4.0 - an XML document gets rendered with my XSL style
sheet, but I want to pass in to that same style sheet a separate XML
document as an XSL parameter.  I can pass it in, but when I try to use
that parameter in an for-each XPath "select", I get an error.

   <xsl:for-each select="$my_xml_param/one/two">

Can this be done?

I'd copy and paste in the error, but it's a colleague of mine who ran
into this so I can't run it and get the output.

TIA.

Hardy Merrill