Here's how it breaks down:
The components in the eTorque Hemi equipped trucks that are different from the regular Hemi trucks are as follows:
1) The alternator is replaced with the Motor Generator Unit (MGU), also referred to as the Belt Starter / Generator (BSG).
2) There is a 48V briefcase sized battery pack in the rear of the cab behind the seatback, and also includes the voltage regulator and converter.
3) The single serpentine belt accessory drive on the front of the motor now has two belts, the water pump is now driven on its own belt from the crank, the the extra is the belt that the MGU is attached to, and drives the crankshaft pulley as well as the ac compressor. The regular Hemi uses a single belt to drive all the accessories.
4) The associated wiring harnesses.
5) The transmission itself.
Everything else is identical from truck to truck. The "regenerative braking system" is just the MGU adding drag to slow the motor / charge the battery.
Bolting on the crank drive pulley, the MGU, and installing the battery pack is the easy part. Heck, even the trans swap is "easy". It's the wiring harness installation and programming where it gets into factory only capabilities. The number of harnesses and computers that would need to be flashed, replaced, programmed, etc is beyond the scope of my understanding at this point.