2 of my 3 children have LI, and we deal with the scaly scalp issue all of the time. My children's dermatologist gave them a prescription for DermaSmoothe FS. It is an oil that I put on their scalp and then put a plastic shower cap over it to keep the air out (and the oil in) and a wave cap over that (like a thick pantyhose material) to keep the showercap from slipping off. The wave cap can be purchased at a beauty supply store for about a buck. We do this at night before bed, they sleep in it, and in the morning they sit in the tub. I shampoo them twice to get the oil out and use a metal cat/dog flea comb (from the pet store) to comb out the scale. The freshly exposed scalp will be sensitive, so you want to wash first as water touching the exposed scalp after combing will sting a bit. (If you give them Motrin 30 minutes before getting in the tub that might help with the sting.) The oil softens and loosens the scale so it comes off the scalp and slips off the hair easily.
You will be surprised how much nicer their hair lays after doing this treatment. My son is 6 and has short hair. He tolerates this process well. My 3 year old daughter doesn't. I keep her hair shorter, but it is naturally curly and tangles a bit in the process. Also because of her age she hates this process and whines through the whole thing. She takes a lot of patience and coaxing. Expect to spend about 30 min - 1 hour combing, depending on how cooperative your daughter is.
You could try the same process with olive oil. I haven't tried it, but I've heard it works too.
I hope this helps. I love how nice they look afterward, and I know it's more comfortable for them, I imagine it helps keep them cooler being able to exhaust heat from their scalp easier too. I'm actually planning on doing their caps tonight myself... good luck!
Daughter, Emma born 9/2001 -unaffected
Son, Andrej born 8/2003 - has Lamellar Ichthyosis
Daughter, Tori born 3/2006 - has Lamellar Ichthyosis