Is there any way to mimic this re-fermentation process when kegging? Or is it even really necessary in the first place?
Bottle conditioning is the most common form of homebrew carbonation. To do it in a keg, you'd use a little less sugar since the process is a bit more efficient in that environment because of the reduced headspace to liquid ratio.
The major difference is in the dispense. With kegging, you have a dip tube that goes all the way to the bottom of the keg. You'd have to either draw off the first pints expecting more yeast to be sucked up, than will happen later or you can shorten the dip tube an inch or so and draw off from above the yeast. Either way, you lose a little bit of beer.