I did this quick illustration to show a friend how I use textures in Illustrator. Turn your texture image to grayscale. Place your texture on a layer above the desired shape. Use a copy of the desired shape to make a clipping mask for your texture image. Apply a blending mode to your texture. Play around with the blending modes and opacity until you're happy with the results.
I just received a couple copies of Chris in the mail from lulu.com. A copy of the book can be purchased from their site here... CHRIS . The book is a little expensive, but that's just because it's so rare!