iframe, help!

i am having difficulties putting in iframes. i am using
Here is an accurate description of my problem:
http://drupal.org/node/69524#comment-890207

I tried the following instructions:
http://tinymce.moxiecode.com/punbb/viewtopic.php?id=6332

I put the the following code inside sites\all\modules\tinymce\tinymce\jscripts\tiny_mce\tiny_mce.js:

this._def("extended_valid_elements","iframe[src|width|height|name|align]")

Is that where it should go?