This is quite tricky. The reason the Qel-Droma robes in-game look like any other Jedi robes is because they all share the same 3D body model. There is only a small number of body models that can be used in KOTOR, ranging from Model A (being the underwear model) to Model J (the Star Forge robes model), which are determined in appearance.2da as columns. While it's possible to add appearance rows in appearance.2da, the number of model columns is hardcoded. In practical terms, this implies that if one were to replace the Qel-Droma robe model, they'd end up replacing the entire batch of Jedi robes in the game.
Now typically there are two workaround for this: either replacing the Star Forge robes model or introduce a new model as a disguise. The latter is ideal for stuff that also covers the head of the wearer, but when the character's head is meant to be visible, then it gets tricky because you'd have to create a new row in appearance.2da for each of the playable heads. Yikes.
Besides, a mere retexture, however well-made it may be, won't cut it if you want to achieve the look on those pictures, simply because the robes models don't quite look like on the pictures.
Depending on the direction you'll want to take for this I'd gladly create a new model quite close to the one in your pics. However, as I'm already working on several projects at the time and because of IRL stuff, I won't create the texture for it. Someone else would have to join in and do that.