All sorted. There was an issue with the orm2dcm file. I reverted to the original file, and have the following in my mwl-cfinrq file:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:output method="xml" indent="no"/>
<!-- overwritten by application with actual values -->
<xsl:param name="calling" select="'SAMPLE_MOD'"/>
<xsl:param name="called" select="'DCM4CHEE'"/>
<xsl:param name="date" select="'20051206'"/>
<xsl:param name="time" select="'115600.000'"/>