odoo/addons/sale/wizard/sale_make_invoice.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
    	<record id="view_sale_order_make_invoice" model="ir.ui.view">
            <field name="name">Create invoices</field>
            <field name="model">sale.make.invoice</field>
            <field name="type">form</field>
            <field name="arch" type="xml">
            <form string="Create invoices">
            	<separator colspan="4" string="Do you really want to create the invoice(s) ?" />
    			<field name="grouped"/>
    			<newline/>
    			<field name="invoice_date"/>
    		   	<separator string="" colspan="6"/>
              	<button special="cancel" string="Cancel" icon="gtk-cancel"/>
               	<button name="make_invoices" string="Create Invoices" type="object" icon="gtk-ok"/>
           		</form>
            </field>
		</record>

		<record id="action_sale_order_make_invoice" model="ir.actions.act_window">
            <field name="name">Make Invoices</field>
            <field name="type">ir.actions.act_window</field>
            <field name="res_model">sale.make.invoice</field>
            <field name="view_type">form</field>
            <field name="view_mode">form</field>
            <field name="target">new</field>
        </record>
        
        <act_window name="Make Invoices"		    
		    res_model="sale.make.invoice"
		    src_model="sale.order"
		    view_mode="form"
		    target="new"        
            key2="client_action_multi"    
		    id="action_view_sale_order_make_invoice"/>		

    </data>
</openerp>