Typically defined as inner bean within a LocalSessionFactoryBean definition, as list element for the "typeDefinitions" bean property. For example:

 <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
   ...
   <property name="typeDefinitions">
     <list>
       <bean class="org.springframework.orm.hibernate3.TypeDefinitionBean">
         <property name="typeName" value="myType"/>
         <property name="typeClass" value="mypackage.MyTypeClass"/>
       </bean>
     </list>
   </property>
   ...
 </bean>