We need an instim-alien object and text to align the bottom in XSL-FO

Question

I have an XSL-FO stylesheet that is used to create a barcode with description text immediately after it. When I launch it through the Ibex FO application, the text is correctly aligned with the bottom of the barcode. When I run it through Apache FOP (this is an older version 0.3x ... I CAN’t change it), the text is aligned up with the TOP barcode (I need it to work the same in both). I really hope there is some solution here. This is what I have:

<xsl:template match="barcode">
    <fo:block>
        <fo:instream-foreign-object content-width="100%" content-height="100%">
            <xsl:call-template name="barcode-3of9">
                <xsl:with-param name="value" select="@value"/>
            </xsl:call-template>
        </fo:instream-foreign-object>
        <xsl:value-of select="description"/>
    </fo:block>
</xsl:template>

It is contained inside a table cell with two columns of these blocks. I'm trying to match the output of an older application, so I can’t put the description in another cell with the barcode, since I need the description to fall on the edge of the barcode, and not all the descriptions are aligned.

Is there a workaround that I can use here? I am pretty much out of ideas.