Liu Wan (or Sixth Finish) is found on the Gallbladder channel on the dorsal aspect of the foot. You will find this point 0.5 cun proximal to the web margin of the 4th and 5th toes. Some references say this point overlaps Gb 43, others say you find the point 0.5 cun proximal to Gb 43. Palpate between these two locations and find the point on your patient.
Check out eLotus' excellent video tutorial on locating and needling this point.