Monika Stramaglia's Clapotis on Machine is a wonderful machine adaptation of the knitty Clapotis. Monika's version is done one the bias, but I wanted a quicker knit, so mine is straight.
For my first attempt:
I used 14 sets of 5 x working position / 3 x resting on the front bed and on the back bed, one needle on each side of the 5 needles and to the left, and used racking one needle back and forth to set the edge stitch. This would be excellent for using up a cone of slippery yarn. (diagonal as per original or straight). However, this used up a lot of yarn, making it about a metre (40") long.
I did another attempt using front bed only but that I had considerable trouble with the cast on (again!) and have officially given up on the e wrap method. My machine doesn't like it one little bit.
Front bed only: I upped the tension to T4.5: 12sets of 5WP/3RP and crocheted the cast on stitches onto the combs, it was slow going at first, but quite happy with it thereafter and will certainly use this method again, leaving the 3 x resting position chains inbetween. I'm just so relieved to have this work, it was the most fiddly. The counter says I did 552 rows and it ended up being 1.5m long.
I will do a diagonal version of the scarf, but not this side of Christmas.