Thinking about it, if you want to just change how the redirect works then you can do that in the redirect method.
/includes/openid/openid_class.php
FIND function redirect($url)
That controls how the page redirects, but as long as the user gets to $url I do not think it matters how the user gets there. Although I think that method is also used to return the user to the index page as well after logging in. You might need to add a second variable to that method for including in a frame or not, then the processOID method could tell it to use the new frame.
Hopefully I'm making sense




