i haven't made the bag yet, but i sat at work yesterday trying to figure out the same thing! (this is for the first shorter bag)
for the increases from 88 sts to 220sts, i think i'm going to do
round: [(kf/b 2 times), m1]* rep around.
(that is, knit 1 front+back two times, make 1).
doesn't that increase by 4 stitches for each 1 stitch, instead of 2.5? my theory was to *kfb,kfbf, rep from * across, reasoning that if i double the number of stitches by kfb in every stitch, that's 176, plus increasing an additional stitch on one-half of the total stitches (44) for a grand total of 220 all around.
it basically turns 2 stitches into 5 stitches (or 2.5 sts for each stitch). knit into the back and front of 1 stitch (2 times), then make one. however, the m1 part means that there are tiny holes in the bag (which i hadn't thought of, until i did it all... oops), but these can easily be stitched closed, OR if you're lining the bag, it doesn't make much of a difference (they're not noticeable, just.. for functionality, it isn't practical to have holes in the bottom of a bag.)
hm, perhaps it was my short hand that was confusing.. probably should have been written [(kf/b) 2times, m1] rep around.