Convert string to nodeset

Hello list,

I guess I am not the first one to ask the following question but I could
not found a clear answer in the faq or in the archive (maybe I just used
the wrong keywords).

I would like to use variables in the select-attribute of a
<xsl:apply-template/>. How can I do that?

I have e.g.
<xsl:variable name="inxPath">/root/inx</xsl:variable>

Then I would like to 
<xsl:apply-templates select="$inxPath/docu"/>

...but I get cannot convert from STRING to NODESET. 

I tried with
<xsl:apply-templates select="xalan:nodeset($inxPath)/docu"/>

...but I get an empty document.

Any ideas, links or tips are very welcome.

TIA
-- 
thorsten

"Together we stand, divided we fall!" 
Hey you (Pink Floyd)