Here are crochet directions from the webpage: Legwear:
...leg warmers will be most appreciated in the dead of winter when temperatures plummet and winds wail, but be sure to have them crocheted and ready to wear.And here is how you would knit these legwarmers: Measure your leg at the thickest part and determine your gauge according to the size yarn you are using. Two skeins of yarn should be adequate for two legwarmers. Of course, larger needles will make the project go faster. Marissa Huber on Flickr used Noro yarn. Any self striping yarn would work well.
Directions are given for size 9-11. You will need two 4 ounce, skeins of 4 ply yarn and sizes I and K crochet hooks.
Gauge: 3 hdc equal 1 inch
Starting at lower edge with smaller hook, ch 30, join with sl st to form ring, ch 2, do not turn.
Row 1: Sc in each ch, join with sl st in top of ch-2, ch 2, do not turn.
Rows 2 through 8: Repeat Row 1.
Row 9: With larger hook, ch 2, hdc in each sc across, join with sl st in top of ch-, ch 2, turn.
Repeat Row 9 to length desired, after last sl st, fasten off
I didn't really use a pattern, I just used a little math and knit a 1 x 1 rib. I kept knitting until they were long enough to stretch up to my thighs if cold weather required. (Courtesy of VanillabeanKnits)