Use "?managedb" in the URL to reach the "Manage Database" page (for OpenERP 6.1)

myaddon.js

openerp.web_myaddon = function(openerp) {
    
var hostname = window.location.hostname,
    params = jQuery.param != undefined && jQuery.deparam(jQuery.param.querystring())

if (!openerp.web_myaddon) {
    /** @namespace */
    openerp.web_myaddon = {};
}

if (params.managedb != undefined) {
    openerp.web.Login = openerp.web.Login.extend({
        start: function() {
            this._super.apply(this, arguments);
            this.database.show();
        }
    });
}

};

myaddon.xml

<?xml version="1.0" encoding="utf-8"?>
<templates id="template" xml:space="preserve">

<!-- Login page without ManageDB -->
<t t-extend="Login">
  <t t-jquery="div.footer" t-operation="replace">
    <div class="footer">Powered by <span class="openerp">OpenERP</span></div>
  </t>
</t>

</templates>