How to configure hibernates TransactionManagerLookup within an OSGi container

Issue

I have the following spring LocalSessionFactoryBean configuration. What is the correct way to configure hibernate.transaction.manager_lookup_class ?

    <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">

             <property name="mappingResources">
              <list>
                <value>TestMessage.hbm.xml</value>
              </list>
             </property>

             <property name="hibernateProperties">
                     <props>
                             <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
                             <prop key="hibernate.show_sql">false</prop>
                             <prop key="hibernate.format_sql">true</prop>
                             <prop key="hibernate.cglib.use_reflection_optimizer">true</prop>
                             <prop key="hibernate.jdbc.batch_size">10</prop>
                             <prop key="hibernate.transaction.manager_lookup_class">?</prop>
                      </props>
             </property>
             <property name="dataSource" ref="dataSource" />
     </bean>