<reference name="after_body_start">
    <block type="core/template" name="any_unique_name_here" template="path/to/your/template.phtml" />
</reference>

<reference name="after_body_start">
    <block type="core/text" name="any_unique_name_here">
        <action method="setText">
            <text><![CDATA[
<script type="text/javascript">
console.log('It works!');
</script>
]]></text>
        </action>
    </block>
</reference>