Earlie this week the AuthHelper add-on was updated.
If you use browser based auth then you can just specify the URL of the login page and the credentials.
It will attempt to submit the form using a browser which means you do not have to specify the exact request or set of requests.
This is known to work with some SSO provides.
It will not work with Google SSO as that blocks any browser controlled by software.
To start with the auth method will only support forms with the username and password both visible.
The plan is to support forms where you have to fill in the user name, submit the form and then fill in the password.
Cheers,
Simon