The only pattern is 2x2 ribbing so you need to increase sts by 4s - 88, 92, 96 etc. Whatever you need to make it an inch or so larger, but the decrease is set up for multiples of 12, so maybe going for 96 as a CO will work, it all depends on your gauge. You can knit the ribbing for a row or two more, then switch to stockinette. Follow the pattern for the striping if you're going to use that. Where it says knit in gray until 6 inches from the CO, make that 8 inches, then start the decs. If you have a st number that isn't a multiple of 12, do the decs as a different number. Say if you have 88 sts, that's a multiple of 11, so you would start with the row that's k9, k2tog all the way around.