Getting reference of DataSourceUserManager

[Gerald]

In orion-application.xml, one can specify the use of DataSourceUserManager 
which allows Orion to manage user information via a database.

How can I get a reference to an instance of this user manager so that I can 
add, delete and look up users and groups? Should I just instantiate my own 
copy of the object, or must I get it through Orion? 

Thanks.