Is it possible to modify the html code of a page on the fly?

Question

proxy

Computer with Win7, Internet Explorer 9, in a domain, has local admin rights.
The essence of the problem: you need to embed your javascript in the code of the resulting page (optimization of filling out forms). The nuance is that group policies have disabled the ability to set a proxy in the browser.

Answer 1

Bring up a local server, add it to the trusted zone , set the trusted zone to a low security level (or manually allow cross-site scripting). After that, the script hosted on the page in your domain will be able to open the page in a window or frame and talk to the DOM.

Answer 2

I open localhost in the browser with the following code (I left only the meaningful code):

<iframe id="frame1" width=100% height=100% src="http://адрес.ru"></iframe>
<script>
$(document).ready(function(){
$('#frame1').contents().find('img').hide();
});
</script>

localhost in trusted hosts, security is low, still getting a thrash:
Error: Access denied.
Maybe something else needs to be tweaked?