This will sound a bit rambling. Don't know this pattern, and you may need a second pair of needles but do you knit so many rows, knit along y stitches and then then turn, knit x no of stitches, turnagain and knit a strip from these next x stitches This would then be knitted into the space where it was taken from and the front knitted as usual. This is for a double pocket.
For a single lining you knit so many rows, knit some stitches then rib x stitches in the middle, turn and just on these x, knit y rows ribbing and cast off? Then using a second pair of needles (or one with knitting on it), cast on the same amount of stitches as the ribbed section and knit up the same number of rows from the end of the ribbing, or as instructed. Now with the front piece, knit along to the cast off stitches and insert the strip you just knitted. The ribbing just gets sewn down. I have even had to pick these up from the top of the ribbing.
