I knitted them using my toe up Andersson method with the Andersson heel Mach II (improved version.)
This is the pattern. Simple to do. I changed from 2x2 to 4x4 every 10 rows, but alternating where the 4 x4 lay.
EDIT: the pattern is only on the instep and front of leg. teh rear of leg is plain 2x2 rib. I used travelling sts to create the pattern, no increasing or decreasing. So, for example, after the first 9 tows of 2x2 ribbing, on the 10th round I purl one, hold next purl at back, knti 2, purl the held stitch, p2 and hold next 2 sts to front, purl 1 and then knit 2 held at front. As you do dit, it will become obvious how you do it. then I knti a further 9 rounds afetr this one and on the 10round, I travel back to 2x2. Now the importnat bit is that wehn you are ready to travel back to 4x4 you do not do the same as for the first swtich to 4x4. Instead you p2, hold 2 to front, p1, knit 2, hold p st at back, knti 2, p the held stich, p2, hold 2 to front, p1, knit the 2 held. I have written this as I try to picture in my mind what I did so this is not foolproof. However, if you DO IT, it will become clear.