I don't know how to accomplish what you're trying to do. You may need to talk to the IDX provider.
I have my listings "fed" onto my pages simply via the link provided by the MLS, and then using an iFrame within the site.
Look here and see what I did with my site:
http://www.wallenpaupacklakeproperty.com/realestate.htmWhen you click on the links to the left, the IDx listings display in the center area, which is an iFrame.