Ponytail Germination:
1) Remove flakes from around the hard seeds inside. (If already cleaned, ignore this step)
2) Sand the hard shells with rough grit sandpaper, then pour hot water over them and let them soak for 24 hours.
3) Use a Cactus/Succulent potting mix. Moisten the soil and press the seeds lightly into the surface. Cover with a very fine layer of sand. 
4) Use a heated propagator to keep the soil temperature above 68 F at all times. 75+ would be Optimal.
5) Keep the container lightly moist by misting. Cover the container with plastic until germination. Remove the plastic once per day to allow excess moisture to escape.
6) Keep the container in a brightly lit area but with some shelter from midday sun, which may burn new leaves. 
7) As with any Tropical or Exotic, Germination will be erratic, so expect sprouts in 1 to 3 months depending upon the time of year and amount of light and heat the seeds experience.