I love the way the cross stitch looks on the spine of a book. Stitching in the signatures with this technique is a lot more labor intensive than using the pamphlet stitch, but for certain projects it's worth the extra effort.
For this method you will need to punch 7 holes in each signature. I've created a tutorial that shows the sewing technique to get the stitching right. I hope you find it helpful.
Here's one of the journals I made that features the cross stitch binding.