Yes this is possible, though I don't think it's documented very well (it's in queryCustomView.xsd). Each column may have a set of properties associated with it, but the only one that is used currently is called "columnTitle". The XML would look like this:

<column name="Id/age/AgeInYears">
   <properties>
      <property name="columnTitle" value="Age"/>
   </properties>
</column>