Slaaneshi Traitor IG?
Have you thought of using codex Eldar or Dark Eldar to run them?
The armour is right with both codices and the heightened initiative represents the Slaaneshi side of the equation very well. Shuriken weapons are rare bolter variants, splinter weapons are expensive needle weapons. Venoms make good civilian aircars. Wracks are combat servitors on steroids.
Actually, the Eldar Corsairs list from IA11 would probably work best. Regular dudes have lasblasters (custom lasguns bought at great expense), Venoms are aircars, Wave Serpent based vehicles are Valkyrie variants with illegal weaponry. The regular guys have high Initiative, but not too high. Harlequins can represent the chosen cultists or even Daemonettes. You can also take 1 squad of Dark Eldar Warriors (elites troops with needle rifles) and 1 Elites or Fast Attack choice from codex eldar (or Rangers) as an Elites choice.
I've been planning on using the DE codex to run Gland War Veterans, myself.