Steam it. Then let it dry on a flat surface. No weight/books on top.
My wife's an interior designer, I install area rugs all the time. Rug manufacturers always say "do not force the rug flat, let gravity do it over time". Putting the books on top was a bad thing.
![BigThumbUp](http://www.the370z.com/images/smilies/biggthumpup.gif)
Something about breaking fibers.