I did pretty much all of what you did after reading your reply. I used an old E-string from my guitar. I tried taping batteries to it to use as handles, but they kept slipping so I found using heavy duty work gloves and wrapping the string around my hands worked best.

I found placing the string underneath the top part of each cell and then pulling down with force worked best, cut through the glue like butter after a bit of pressure. Be very careful not to go too fast; I got a bit ahead of myself on the last cell (too confident I guess) and cut into the cell, causing a short and a mini-flame. Thankfully it died down immediately. I placed the leaked battery inside a box with sand and placed it outdoors until I can dispose of it in the proper way.

Other than that, it was a matter of applying a lot of alcohol on the residue and then scraping it off using a metal spatula with rounded corners to avoid scratches. While process took about 1hour (including the incident). So, doable but be very careful!