Purtroppo no!
Ho fatto questa rapida prova che usa il mapping via xml:
***********  Mapping ***********
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
                   namespace="demo"
                   assembly="demo">
  <class name="Region" table="Region" lazy="false">
    <id name="Id" column="RegionId" >
      <generator class="identity" />
    </id>
    <property name="Description">
      <column length="50" sql-type="varchar" name="RegionDescription"/
    </property>
  </class>
</hibernate-mapping>

***********  Configurazione ***********
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-configuration xmlns="urn:nhibernate-configuration-2.2">
  <session-factory>
    <property name="connection.connection_string">Data Source=.
\SQLEXPRESS;Database=Northwind;Trusted_Connection=yes;</property>
    <property name="dialect">NHibernate.Dialect.MsSql2005Dialect</
property>
    <property
name="connection.provider">NHibernate.Connection.DriverConnectionProvider</
property>
    <property
name="connection.driver_class">NHibernate.Driver.SqlClientDriver</
property>
    <property name="show_sql">false</property>
    <property name="connection.release_mode">auto</property>
    <property name="adonet.batch_size">500</property>

    <!-- Mapping assemblies -->
    <mapping assembly="demo"/>
  </session-factory>
</hibernate-configuration>

***********  Applicazione ***********
using System;
using NHibernate;
using NHibernate.Cfg;

namespace demo
{
    class Program
    {
        static void Main(string[] args)
        {
            var configuration = new Configuration();
            configuration.Configure("hibernate.cfg.xml");
            ISessionFactory factory = configuration.BuildSessionFactory
();
            using (ISession session = factory.OpenSession())
            {
                IQuery q1 = session.CreateQuery("from Region r where
r.Description like :desc");
                q1.SetParameter("desc", "zon%");
                q1.List();

                IQuery q2 = session.CreateQuery("from Region r where
r.Description like :desc");
                q2.SetParameter("desc", "zone%");
                q2.List();
            }

            Console.Read();
        }
    }

    public class Region
    {
        public virtual int Id { get; set; }
        public virtual string Description { get; set; }
    }

Le query eseguite sono:
exec sp_executesql N'select region0_.RegionId as RegionId0_,
region0_.RegionDescription as RegionDe2_0_ from Region region0_ where
(region0_.RegionDescription like @p0 )',N'@p0 nvarchar(4)',@p0=N'zon%'
exec sp_executesql N'select region0_.RegionId as RegionId0_,
region0_.RegionDescription as RegionDe2_0_ from Region region0_ where
(region0_.RegionDescription like @p0 )',N'@p0 nvarchar(5)',@p0=N'zone
%'

C'è qlc di sbagliato nel mio mapping ?
Grazie
Claudio