I was probably a little light in my description. I didn't just attack the hair with a comb, I was careful about it. I did comb from the top side and the underside as you described. I just kept working it with the comb. Even after, the hair still has some wave to the body of it, but it's mostly straight. It just takes patience, a little privacy, (lol) and a little effort. It's not difficult. I have a couple of aftermarket Olsen heads I'll be straightening out next.
Here's the pics of the before and after on the VeryCool Milla head.
Ryan
Can I ask where to get the yellow spandex top? It looks like it can pass off as an X-Men suit for a custom kitbash project!