I am planning on using a 40watt soldering wand, the same iron I've been using for quite some time now, but with a much larger tip for hopefully increased thermal heat capacity. I would be using a hammerhead tip, but to do so, I'd have to bore threads into one for it to fit my iron.
If that doesn't work while I'm practicing on already dead cells, I'll use a soldering gun, but I've read that the increased temperature has more of a risk for destroying the cell's vents/seals.
the pack is to be a double stick-nunchuk pack (only style that will fit within the space avaliable). I'm still not sure what kind of jig I'll use while assembling the linear sticks, but I'll find out soon enough.
Thankyou to everyone for your input!!