Before I read to the extractor part, I had you a plan. Now I'd say welding a nut or having the machine shop use one of those crazy laser things on it is your quickest way.
The Dremel way could work as well. I had a case cover strip all the phillips heads one time, so I figured I'd grind them until they were studs, pull the cover, then put vice grips on what was left. I found that the friction heated them up to the point of loosening by hand before I got any of them totally ground. Maybe get yourself a tiny butane torch. Sometimes a Bic lighter, patience, and some penetrating oil gives you that extra push. If a Dremel slot wouldn't work, and you're comfortable with it, grind two sides of the big allen head off so that a wrench or vice grips could grab the outside flat. Those particular screws are large enough that it may work.
There's a lot of ways to approach it so read around the net and get creative if you have to.
The Dremel way could work as well. I had a case cover strip all the phillips heads one time, so I figured I'd grind them until they were studs, pull the cover, then put vice grips on what was left. I found that the friction heated them up to the point of loosening by hand before I got any of them totally ground. Maybe get yourself a tiny butane torch. Sometimes a Bic lighter, patience, and some penetrating oil gives you that extra push. If a Dremel slot wouldn't work, and you're comfortable with it, grind two sides of the big allen head off so that a wrench or vice grips could grab the outside flat. Those particular screws are large enough that it may work.
There's a lot of ways to approach it so read around the net and get creative if you have to.