Navigating through the document using variables

Hi,
I have a variable initialized at runtime with the path to some element
(something like this /elem1/elem2/elem3). Can I use this variable to
navigate to the elem3 in another variable that is initialized with the
document like this:
<xsl:variable name="doc" select="document('./somedocument.xml')"/>

In other words I would like to use this string to retrieve a node-set from
the document, something like this:
	$emps[$ref]
Regards,
Janusz