Would really like to get my hand on that battery holder. Still, with a little improvisation:
Not the most convenient thing, but at least I know the flash works. That's four Sanyo Eneloop AA batteries in serial. I cut a few strands of copper from short piece of braided 10 AWG ground wire and affixed them to the battery contacts with Kapton tape. The bottom pair of batteries are unlinked and touch the unit's contacts easily, without modification. I added a bit of foam buffer on the left side for spacing (covered in tape to avoid shorting, just in case). Works perfectly, but of course it takes a few minutes to set up.
Figured I'd post it to give hope to anyone sharing my affliction.
Edit: Forgot to add that the cover does fit properly over the batteries. And please excuse the low-light iPhone photo.