The books don't cover winter clothing specifically, they cover
techniques for sculpting that could be used to make winter clothing, if
that's what you want to make. Many of the techniques for making a flag,
or anyt other long, flowing piece of cloth out of epoxy putty, can be
extended to making a great coat. Sculpting is sculpting.
I'll add to
gburdon's
sculpting suggestions that you'll want to let the putty set up for a
while (how long depends on what brand of epoxy putty you use. I use
Magic Sculpt, which takes about an hour to set, and about two to cure,
so 20 to 30 minutes is a good time to wait), after rolling it out,
until it's just starting to set, but is still malleable, and then start
adding it to your model. That way, you can get the flowing rolls and
wrinkles you need, and the putty will be stiff enough to hold the
details without sagging, or being easily disturbed if you touch it.