ActiveRecord lock - defining glue lines at runtime

When using Castle ActiveRecord, can you tell at runtime which connection string to use?

As I understand it, ActiveRecord needs to be initialized only once during the lifetime of the application, which means that the database initialization strings must be set up before initialization.

However, it is still possible to determine connection strings at runtime - that is, what if the web application doesn't know which database to use until the user is logged in?