Henderson is basically all roleplay. The closest he had to something you'd need mechanics to replicate is the Backstory of Doom: you're going to want as many skill points as you can get your hands on for the most esoteric of professions.
Beyond that... he used a shotgun (not something you can replicate, not core to the character), he drank a lot (not something you need crunch to replicate), he was crazy (not something you need crunch to replicate)... you see where this is going.
Easiest class for him is an Empiricist Investigator.
