They are created using a even-count circular peyote stitch around a large flat sequin. Beaders who make jewelry also use this stitch to attach cabochons to leather or ultra-suede. I don't feature this stitch in its entirety in any of my books, however, the first round of beads is stitched with the basic bead back stitch, which is covered in every one of my publications. Here's a link to a book, Best of Bead & Button Magazine which provides good instructions that can translate to secure sequins (and other round objects) to fabric.
Don't forget to be sure your fabrics are properly stabilized....I like to use Pellon non-fusible lightweight interfacing to support the weight and prevent buckling of the surrounding fabric.