<xsl:template match="/">
<!--.......................................-->
 <xsl:apply-templates select="//vLocalConnection">
  <xsl:sort data-type="text" order="ascending" select="@ContragCutName"/>
 </xsl:apply-templates>
</xsl:template> 

xml:
<root>
    <vLocalConnection ContragCutName="d"/>
    <vLocalConnection ContragCutName="c"/>
    <vLocalConnection ContragCutName="b"/>
    <vLocalConnection ContragCutName="a"/>
</root>

xsl:
<?xml version="1.0" encoding="Windows-1251"?>
<xsl:stylesheet id="style1" version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> 
<xsl:output method="html" encoding="Windows-1251"/>

<xsl:template match="/">

<xsl:variable name="MyVariable" select="'ContragCutName'"/>
<xsl:apply-templates select="//vLocalConnection">
    <xsl:sort data-type="text" order="ascending" select="@*[local-name()=$MyVariable]"/>
</xsl:apply-templates>
</xsl:template>

<xsl:template match="vLocalConnection">
    <xsl:value-of select="@ContragCutName"/>    
</xsl:template>
</xsl:stylesheet>