This is totally natural ingredients, won't hurt baby's eyes and will soften scales so they come off. Well, at least it does for me and I have lamellar icthyosis.
Get his scalp wet, then rub peanut oil all over it. I've done it to myself several times, and either just leave it on all day if I'm going to be home, or else wear a showercap to bed. After about 8 hours of this, I just wash my hair twice to get all the oil off, and the scales come off as I wash my hair or can be very gently and easily pulled off.
If that doesn't help, repeat the process within the next two days.
Some people are really allergic to peanut oil. I suspect any other nut or vegetable oil will do.
Be careful not to pull out the hair when you take off the scales.
As always, check with the dermatologist/pediatrician to make sure it won't hurt the baby.
If I did this twice a week instead of once every few months, I doubt I'd even need to use any special shampoos. I just don't sleep well with a showercap on, and don't want to feel like I can't go out in public since my hair looks like I washed it grease!
T-Gel has never really worked for me. I do use DHS shampoos and like them, I like P&S shampoo. However, except for the P&S shampoo, the scent on those heavy tar based ones burns my nostrils and eyes slightly so I'd avoid using it on a baby.
You're right about working the scales off a person can develop bald patches/thin hair as it blocks the hair from growing out. When I was a kid, my hair was really thin for that reason. I was lucky and it all grew back in when I was able to take better care of myself.
I am female, and was born in 1972 with Lamellar Ichthyosis.