Have a read through the new Dark Eldar codex, as it helps set them apart from their more apathetic and or wandering kin. That plus the write up on the children of the thorns is really all you should need to make them distinct from the other three eldar factions operating in the expanse.
There's also some information on the GW specialist games website in their battlefleet gothic section, including special weapons we're not likely to see RT conversions for until the Xenos book comes out.
I know it's not as ideal as having all of it laid out in one book for the system you're using, but it's probably better in the long run for you to peruse as much information as you can.
)I remember flicking through the old one and thinking how it had nothing of value if you didnt play TT.So i'll try and browse it then decide.