Here is an XSLT 1.0 stylesheet that does the trick here for me (tested with Saxon 6.5.5):
Code:
<xsl:stylesheet
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:icns="urn:NewBusiness_ABC"
version="1.0">
<xsl:template match="@* | text() | comment() | processing-instruction()">
<xsl:copy/>
</xsl:template>
<xsl:template match="*">
<xsl:element name="{name()}" namespace="{namespace-uri()}">
<xsl:copy-of select="document('')/xsl:stylesheet/namespace::*[local-name() = 'icns']"/>
<xsl:copy-of select="namespace::*[not(local-name() = 'icns')]"/>
<xsl:apply-templates select="@* | node()"/>
</xsl:element>
</xsl:template>
</xsl:stylesheet>