lack of any fine feed along the X axis
Surely the normal lathe carriage feeds are available ?
Remove the lathe chuck to avoid getting caught by it, select a suitable carriage feed and direction, engage the half nuts (or feed shaft if applicable) & run the lathe spindle to feed the carriage under the separately powered milling head. What would normally be considered the lathe Z axis would become the milling machine X axis.
Still have the small table & lack of rigidity normally associated with a "proper" milling machine, though.
Nigel B.