I casted on 40 stitches. I worked the pattern exactly as described, but I did 16 rounds of increases (instead of the 14 prescribed in the pattern).

LEFT MITT:
I distributed the needles as 16-12-12, worked
15 rounds of K2-P2 ribbing. Then worked the cable pattern starting on stitch #7 (described below),
13 rounds of plain stockinette/cable (no increasing),
16 rounds of increasing every-other-round (and casting off 16 stitches on the 16th round)
1 more round without increasing,
15 rounds of K2-P2 ribbing.
Finally, I cast off all stitches in pattern.

RIGHT MITT:
I distributed the needles as 12-12-16, and worked the same way as for the left mitt, except I knit two stitches from needle 1 onto needle 3 at the end of the 15th round of ribbing to accommodate the cable pattern. Then my needles were distributed as 10-12-18. Next, I started the cable pattern on stitch #25 (the third stitch on needle #3). On the final round before beginning the second ribbing section, I replaced the two borrowed stitches onto needle 1 so needles were once again distributed as 12-12-16. Then I worked 15 rounds of K2-P2 ribbing, and then cast off in pattern.

CABLE PATTERN
LEFT MITT:
Starting at Stitch #7 after the ribbing, the 10-stitch cable pattern is:
Round 1: P2, K6, P2
Rounds 2-4: P2, K6, P2
Round 5: P2, C6B, P2
Rounds 6-8: P2, K6, P2
Repeat Rounds 2 through 8 3 more times for a total of 4 cable sections.
Round 30: P2, K6, P2 (this is the same as round 1 so both ends of the cable design look the same).
RIGHT MITT:
Cable pattern is identical to left mitt, except cable design starts at stitch #25 and I did C6F (instead of C6B’s).