Hey knoerzer,
Well after reading what little they had on this guy at Wookieepedia. I would stick with the Mad Scientist theme. But go with some SA's like Homicidal Surgery, Paralysis, Poison +10 and +20, Poisoned Blade, Virulent Poison +20, Kouhun Infestation, Dominate, or Doctrine of Fear.
Maybe even take your Custom Special Abilities idea's and reword some of these that I mentioned.
Here's one I've been working on.
Continued Paralysis: A living enemy hit by this character's attack is considered activated this round; save 11. On a failed save, the paralyzed character can make a save attempt once per round thereafter until a save is made restoring movement; save 11
The Bounty Hunters are my favorite characters and this would go well with one of them.
The Celestial Warrior's Embrace of Pain SA sounds cool too.
