eiru_crm/template.xml

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
  <data>
    <template id="assets_backend" inherit_id="web.assets_backend">
      <xpath expr="." position="inside">
        <script type="text/javascript" src="/eiru_crm/static/src/js/custom.js"/>
      </xpath>
    </template>
  </data>
</openerp>