I am re-opening this because I'd still rather know if it's possible to set the users state via the API.
If I log them in through an SSO token, then it automatically creates an account. After that, they can login through the site simply by going to their settings and creating a password. They don't have to go through me.
I need to be able to automate enabling/disabling access to the Tender support forums for certain users. It would make my job a whole lot easier.