You're right that it's some sort of coarse taper thread, I'd check for you but I don't have any way to tell what it is after I have it in my hand.
Why not something like one of these: Sears.com
and just drill it out? The outer case and threads, etc. are some type of brass/yellow metal so it should be soft. If an easy-out doesn't work, some sharp needle nose after you drill it shouldn't be too crazy. Then you don't have a make-shift setup