Nevermind, figured it out--
We're using the Advanced Image Viewer XML package (shoulda mentioned that before,) and there is no <xsl:template name = "Variant"> as mentioned in the "merge animation instructions, so I had thrown the script call into the <...mode="Variant> template instead, which did not work. I just moved it to <xsl:template name="VariantInfo">, and that appears to have done the trick.
Bill Imbrogna
Using MSx9.5.1 with a couple MoreStores.