Passing a "callback" name to ixsl:schedule-action

Hi,

with Saxon-CE I've used a typeahead "library" which would accept both
the JS function to be called and the callback as params:

<!-- caller -->

<xsl:call-template name="typeahead:load-xml">
    <xsl:with-param name="element" select="."/>
    <xsl:with-param name="query" select="$text"/>
    <xsl:with-param name="uri" select="$results-uri"/>
    <xsl:with-param name="js-function" select="$js-function"/>
    <xsl:with-param name="callback" select="ixsl:get(ixsl:window(),
'onresourceTypeaheadCallback')"/>
</xsl:call-template>

<!-- library -->

<xsl:template name="typeahead:load-xml">
    <xsl:param name="element" as="element()"/>
    <xsl:param name="uri" as="xs:anyURI"/>
    <xsl:param name="query" as="xs:string"/>
    <xsl:param name="js-function" as="xs:string"/>
    <xsl:param name="callback"/>
    <!-- if the value hasn't changed during the delay -->
    <xsl:if test="$query = $element/ixsl:get(., 'value')">
        <xsl:value-of select="ixsl:call(ixsl:window(), $js-function, [
ixsl:event(), $uri, $callback ])"/>
    </xsl:if>
</xsl:template>

Now I want to replace all custom HTTP-related functions with
<ixsl:schedule-action http-request="">. So I picture something like
this:

<xsl:template name="typeahead:load-xml">
    <xsl:param name="element" as="element()"/>
    <xsl:param name="uri" as="xs:anyURI"/>
    <xsl:param name="query" as="xs:string"/>
    <!-- if the value hasn't changed during the delay -->
    <xsl:if test="$query = $element/ixsl:get(., 'value')">
        <xsl:schedule-action http-request="map{ 'method': 'GET',
'href': $uri, 'headers': map{ 'Accept': 'application/rdf+xml' } }">
            <xsl:call-template name="?????????"/>
        </ixsl:schedule action>
    </xsl:if>
</xsl:template>

So <xsl:call-template> functions like a callback here, but I cannot
pass template name as a param. Of course I could hardcode some name
like "typeahead:xml-loaded", but I would prefer not doing that.

Is there an idiomatic Saxon-JS solution to this?