We have ichthyosis-en-confetti, which is very similar to EHK except it doesn't blister.
I know I've posted this in response to a few other threads, but generally we file with 100 grit emery boards. My husband uses a Dremel, but Nathan is 2 and terrified of it, so we just file him. We use Safeguard soap, Head & Shoulders, and St. Ives Apricot Scrub/Radiance in the shower. Nail nippers are much better than clippers on the nails, plus they can cut back the cuticles and trim callouses.
For cream, we use Cetaphil or Jergens Ultra Healing. We put lacrilube in the eyes at night. Brian uses Tazorac once in a while - 1 day of use causes all the thick stuff in his armpits to come off about 4 days later.
All you can do is try some things and read through the old posts. I don't know of anyone else here that has PPK specifically, but many things that others do may very well apply to your daughter.
Ichthyosis-en-Confetti Type 2
Husband, Nathan - 10, Elliot - 7, Oliver - 4, all affected.
I also have an unaffected daughter, age 8.
email: jennifer at confettiskin dot com
facebook - find me on "ichthyosis mommy spot" or "friends of ichthyosis"