How to set the port portion for same origin policy?

I know that document.domain sets the domain portion of the same origin policy. How to set the port portion for the same origin policy?

Details

I can use document.domain to set the domain portion. This sets the port portion to null. By default the document inside iframe sets the port portion to 80/443. So the same origin policy fails and the parent JS will not be able to access the iframe content document object. So is there a way to set the port portion of the same origin policy in the parent JS?