CRM 2011: How to hide Ribbons toolbar of a custom entity inside an iframe?

I have Entity B loaded in an iframe of Entity A. I'd like to hide the ribbons on the Entity B (as well as the left navigation panel).

I found this code and it does work (http://bingsoft.wordpress.com/2010/09/09/mscrm-2011-hide-areas-of-a-form/)

// hide ribbon toolbar
window.top.document.getElementById(“crmTopBar”).style.display = “none”;
window.top.document.getElementById(“crmContentPanel”).style.top = “0px”;

But I have some difficulty to get the code to work in iframe. I use the onReadyStateComplete event on the iframe and pass the executing context.

var iframe = eContext.getEventSource();

I don't know how to access the iframe elements to hide stuff.

Thanks.