See clip from Attorney Rajiv S. Khanna's conference call video that addresses this question.
I do not know. But let me tell you this when you look at the expedite criteria for any government document they are basically the same. If you can show government error or economic necessity or emergency or some kind of humanitarian considerations - there is five or six criteria then apply. As general observation I think it should be possible to expedite H-4 EAD if you meet the requirements. Theoretically it is possible to expedite the H-4 EAD.