I had a similar issue, where I was trying to display content from our own site in an iframe (as a lightbox-style dialog with Colorbox), and where we had an server-wide “X-Frame-Options SAMEORIGIN” header on the source server preventing it from loading on our test server.
This doesn’t seem to be documented anywhere, but if you can edit the pages you’re trying to iframe (eg., they’re your own pages), simply sending another X-Frame-Options header with any string at all disables the SAMEORIGIN or DENY commands.
eg. for PHP, putting
<?php header('X-Frame-Options: GOFORIT'); ?>
at the top of your page will make browsers combine the two, which results in a header of
X-Frame-Options SAMEORIGIN, GOFORIT
…and allows you to load the page in an iframe. This seems to work when the initial SAMEORIGIN command was set at a server level, and you’d like to override it on a page-by-page case.
All the best!