[keycloak-user] User registration outside of Keycloak and automatic authentication,

Hi All, I'm trying to integrate Keycloak into our project and I'm running into the following problem. We have a pretty involved registration flow, so my idea was to go through that flow and create users in Keycloak via admin REST API. That works fine but I end up with a user that is not authenticated after registration. Is there a way to register users outside of keycloak and then end up with an authenticated SSO session? I've seen this thread http://lists.jboss.org/pipermail/keycloak-user/2016-October/008018.html from two years ago, and it proposes writing a custom Authenticator. Is that still the easiest/only option? Thanks for any pointers, Andy