hmmm, well I hope my directions are good. ;-)
There are a total of 18 y-seams (also called inset or set-in seams) in the entire quilt, so it's not like you have to make one for every block. The angles for the y-seams are shallow (120 degrees on one side, 240 degrees on the other), and the pieces to be put together are large. I believe this makes for a much easier y-seam than when the pieces are small (and therefore harder to handle) and the angles are sharper. Believe me, I do not like to do y-seams seams either, but I didn't have any problems with the ones in this quilt, once I figured out the best way to make them. (And that method is spelled out in the pattern.)