"Salesperson suggested that the battery case could be opened"
I doubt it: I bought an "accessory kit" for a Gateway camera from Computer Geeks, hoping that the battery might turn out to be usable. Unfortunately (and not too surprisingly), it's made like the other camera batteries, not a Z battery. It looks to me like the plastic was quite thoroughly glued/welded, and would need to be cut, rather than just pried, open. I.e., no easy and tidy reassembly.
Even more unfortunately, compgeeks.com has sold out of the kits (they still have a version for a different camera that has AA batteries, so don't be fooled), which blows away my Plan B: buy several and use them in my own projects. So, if you doubt mypessimistic evaluation, or have a compatible camera (I think the model number was "DC-T50"), drop me a note: I'll sell this one cheap.
I think the best chance for an alternative would be to find a battery about 3mm shorter than the original, and make a PC board to glue onto the end of it that remaps the contacts.
Ran