rethreaded the spokes with a rethreading tool we have at our shop. we do it all the time when we dont have the correct length spoke to use for a replacement, as long as we dont get into the butting of course.

its been done before, theres a few small companies making cogs that are drilled for it. http://tomicog.blogspot.com/ for example. my buddy has also used a cog from a casette that was already drilled out for weight savings