I am while using SMCF Wordpress wordpress plugin on this website: http://fingelly.com/

As you can tell it uses ajax to publish the shape fields to obtain mailed after which updates the modal.

A few of the nav options to begin get you to a third party IDX (property entries) provider. For instance click the tabs marked agents and also the url changes to fingelly.idxre.com...

As you can tell the html is easy to customize there... I'd attempted adding exactly the same simple modal contact page to my template there but experienced an issue because I am unable to publish using ajax to my wordpress driven site out of this other domain.

I realize this limitation is perfect for security good reasons to prevent xss. How does one suggest working around it within this situation?

For the time being we have simply removed the contact tab.

If you need to simply send information towards the server and never be worried about the response, you produce a hidden iframe around the page and publish the information there. You might create a JSONP call when the data would easily fit in a GET.