Session.Lock is not the only way these lock modes can be used. We can also use overloads on session.Load or session.Get.

var product = session.Load<Product>(1, LockMode.Upgrade);

Note that LockMode.Upgrade or LockMode.UpgradeNoWait changes the behavior of session.Load. Normally it will not call the database, until the loaded entity is being used. When a lock is required, the database must be involved and the entity will be loaded immediately.

We can also specify the lock mode on a query, effectively acquiring locks on all the entities it returns. For an HQL query it looks similar to this:

session.CreateQuery("from Movie m where m.Director = :director")
  .SetString("director", directorName)
  .SetLockMode("m",LockMode.Upgrade)
  .List<Movie>();