pos_select_cashier/views/res_users_views.xml

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
    <data>

    <record id="res_users_form_view" model="ir.ui.view">
        <field name="name">res.users.form.view</field>
        <field name="model">res.users</field>
        <field name="inherit_id" ref="point_of_sale.res_users_form_view" />
        <field name="arch" type="xml">
        	<xpath expr="//notebook/page/group/field[@name='ean13']" position="after">
        		<field name="cashier_password" />
        	</xpath>
        </field>
    </record>
    </data>
</openerp>