Of course, there is no true answer about what Colletta might have done. I'm wondering if there was a mix. For instance, I can't see Colletta spending the time to ink all the lines on the girls pants. I think he would have just made it a solid cover.
Actually that cross- hatching was probably done with zip-tone shading film, not by hand.
Before computers, artists would cut out transparent film, usually in a dot pattern, sometimes in a hatch or cross-hatch, and apply it over a certain area of artwork.
I remember playing with the stuff when I was 12 years old. Still have some tucked away.