Mark,
My scalp is most easily cleared when it has been wet for a long period of time, like when it has been very hot and I keep my head wet by wearing a bandana that I constantly rewet to stay cool. Then I take the shower massage and pressure wash my scalp and all the softened scale washes out. As far as lubing up my scalp and wearing a shower cap or occluding it in some way I will not do that anymore. I used to do it as a child until I developed an infection from trapping bacteria in my scalp under the cream. The resulting infection permanently killed a patch of hair on my scalp that has never grown back and continually seems to slowly but surely get bigger. If you must put creams on his scalp do not cover it with something that won't let it breath, it may be alright for other forms of Ichthyosis but with EHK it can be a sure recipe for an infection. Use whatever adam is most comfortable with and try to wash every bit of it out when the scales have softened up. Once you get the scales thinned down, routine applications will keep it manageable with minimal risk of bacteria and infections.
Keith.