You might try searching for a baseball type stitch.
What I do is use two needles, one on each end of your thread/string/laceing. Start each needle from the under side one on each side of the seam.
Now just cross them and insert through the seam to the underside of the next spot and pull the needle back out the top and cross again. To finish the seam run the needles back down the center of the seam to burry the thread ends.
There are curved needles available with large eyes that work well.
Ron