How to set and use policy when creating a user using the Notes C API

We want to use the Notes C API to create a user with a policy, and have the user set up using the policy settings such as Mail Server, Mail template, Roaming. We can set the Policy field after creating the user entry, but even though the Policy gets set, it does not pick up the policy settings.

Can anyone explain what values and / or flags we need to set on the REGNewUser call or following NSFNoteUpdate call?