Get Feral Mutagen and go into Master Chymist. The reason for this is that with your natural attacks, you get 3 at full BAB for triggering SA. Pump Str and you can achieve a comparable to-hit to the Gunslinger. Take a level of Spirit Lion Barbarian to get Pounce and land your full attack on the charge.

I'll leave SA-specific optimization to the more experienced members, but the ___strike line of spells are a must for the dedicated sneak attacker.