I had a similar problem to solve in .Net to the one I solved in Java using the ServiceLocator class. I moved the NHibernateSessionManager to a library but needed a way of registering project specific interceptors. Here is the code: 

private void RegisterInterceptor()
{
    if (!String.IsNullOrEmpty(ConfigurationManager.AppSettings["HBM_DAL"]))
    {
        HibernateInterceptor interceptor = new HibernateInterceptor();
 
        foreach (Type t in Assembly.Load(ConfigurationManager.AppSettings["HBM_DAL"]).GetTypes())
        {
            if (t.GetInterface("IInterceptorListener") != null)
            {
                interceptor.Register((IInterceptorListener)Activator.CreateInstance(t));
            }
        }
        RegisterInterceptor(interceptor);
    }
}

The following entry needed to be added to App.config: 

<appSettings>
<add key="HBM_DAL" value="Trigger.Side.Services.DataAccess" />
</appSettings>