I am not an expert about it, and I am not completely convinced it works very often, but...
I think it needs to happen 1,000,000s of times to do any good.
I don't think a thumb switch is going to do any good.
Might try a ghurd controller with 50% more dump load (120W?) as the input power (80W?).
This is an unusual circumstance, and it may be one of those times 2 car headlight bulbs would do the job quite well.
I would NOT recommend that much current into them!
For zapping Ni-Cads (not that I would recommend it as something people should try), I hit them with a very small gauge wire for just a fraction of a second, 2-3-4 times (like tapping a smoke on the Zippo?).
Might need to repeat it.
If that doesn't work, they go into the recycle bin (with tape on the terminals) at OfficeMax, BestBuy, etc.