I tried setting the is_login_provider to true, which then gives a “Sign-in with one of these providers” option at the DSP login (with a missing icon), but when I click on that I get a nice error: “The provider “fbportal” has no associated mapping. Cannot create”.
Also, I can make the portal fb call when doing it directly in the browser, its just not working from a jquery call. So the problem seems to be with sessions or cookies or something.