accessing ie8 iframe using contentWindow.document

[lambing]

is it possible to access an Iframe without a source in IE8 and setting it's content? (e.g. iframe_obj.contentWindow.document)

For example I wanted to get the head tag inside that dynamically created iframe:
iframe_obj.contentWindow.document.getElementsByTagName('head')

Then setting it's content:
iframe_obj.contentWindow.document.getElementsByTagName('head')[0].appendChild(dom_obj);