You could do it simply by add the necessary code for that model. like:

#put it to inherit from mail.threadclass account_move(osv.osv):    _name = 'account.move'    _inherit = ['mail.thread']

Extend the views to add the chatter widget, like:

<record id="view_move_form" model="ir.ui.view">
    <field name="name">account.move.form</field>
    <field name="model">account.move</field>
    <field name="inherit_id" ref="account.view_move_form"/>
    <field name="arch" type="xml">
        <xpath expr="//notebook" position="after">
            <div class="oe_chatter">
                <field name="message_follower_ids" widget="mail_followers"/>
                <field name="message_ids" widget="mail_thread" options='{"thread_level": 1}'/>
            </div>
        </xpath>
    </field>
</record>

The only thing is that normally the openchatter widget is after the <sheet> tag but there is no sheet in the original view, Try it to see how it looks