Sadly there aren’t many programmers left here on the forum but I’m sure one of them might pop up to answer your questions. I can tell you that- most likely- those who have created skits for their pleos used Skitter or Yart. I think IMR can educate you about one or both of them. Being blind they are completely in accessible to me but they’re motion-editing tools. There’s also something called Babe but I honestly have no idea what that one is or what it does. What I would love to see one day is a new, fully functional owner-created pleo personality- something like Dog’s Life for the Aibo.
As far as the possibility of facial recognition, I imagine storing all of the various shadows and facial planes needed for actual recognition to work properly would require a lot of memory and I don’t think pleo has much in the way of extra space in its flash drive. Anyway, best of luck!