Be careful of boxes that have been left in un-humidified conditions, they will suck the moisture out of any cigars you put in them.

You can season boxes just like you would a humidor, or for faster results, wipe them inside and out with a damp cloth and put them empty into your fridge for a few days to stabilize. (this is of course, assuming they are bare wood boxes and not paper covered).

Cedar is not necessary if you are storing boxes or singles in boxes.