Javascript Restriction Help

I am trying to get some data from a page but it uses JavaScript to populate some of the fields. This requires me to load the site into an iFrame to get the desired print out. From there I was hoping to get the source code. However, JavaScript does not allow cross-domain information for security purposes. Is there a way to get the code from the iFrame using JavaScript?

I don't think it's possible in JS since it's not the same domain...
It may be possible to parse with a JS parser like JSON or something, though...