You're replacing NiMHs (1.2V) with NiMHs (1.2V). No shenanigans required, as long as you match the original total pack voltage (same number of cells or integer multiple in series/parallel)
AA cells are cheaper than non-standard sizes, and they're smaller than the OEM cells, which leave the rebuilder plenty of wiggle room for connection wiring and fitting the pack back together.
As to disassembly, I would suggest a sharp scalpel or craft blade and many light strokes along the seams, in lieu of any fancier equipment.