As you know there are probably thousands of these EVEREADY lanterns being thrown away because they are becoming obsolete. But a good quality LED spot light with very high brightness is is very expensive. You can do this modification for about $8 worth of parts, mainly the CREE LED and the Digital Driver Board.
Additional mod you can do it replace the 6 volt battery with rechargeable gel Cell, they fir in just right & cost about the same but you can recharge them for 500 times. this is be my next project.
This is the link to the instructional video: http://youtu.be/ITK7rCiWjq0