Im actually pretty confident that it can be made for TSL, as the torso of the robe looks very similar to the way the sith assassins robes are modelled(The shoulders are the most noticeable to me). The part of the robe that hangs down over his knees will be more difficult, as that would require modelling the robe, and I only know one person who can model armor and robes and make it work in-game-Darth Deadman
, and he hasnt been on Lucasforums for a while. Now as for the hood, I believe you can do one of two things, though the second is much,much easier.
1: You could take the hood from Revan's robe and put it on Starkiller's robe by modelling.
2: You could use Canderis' Hood Mod
, with his permission of course
Of course, this goes for any modder willing to try this out. It looks like a great idea so I would like to see it in-game.