I made this link of a BFF Cowl as part of a swap among some friends on Ravelry. I sent this link off to a friend and received one of my own from a different friend (last photo below). The pattern was fun to knit for a swap but the seaming took some serious thinking. I feel pretty brilliant for making it all work out nicely, even though you can tell where the seam is.
The key to Kitchenering in a pattern is to have a good sense of the Kitchener stitch for stockinette. It roughly goes:
put darning needle through first stitch on front needle as if to knit, pull stitch off; put darning needle through next stitch on front needle as if to purl; put darning needle through first stitch on back needle as if to purl (as viewed from the front), pull stitch off; put darning needle through next stitch on back needle as if to knit (as viewed from the front); repeat until endI view the sequence as 'knit, purl, purl, knit', describing the way that the darning needle goes through each of the stitches.
Having reduced the stockinette Kitchener stitch down to 'knit, purl, purl, knit', it's really easy to modify it from here: you simply flip the darning needle's direction from this base pattern for all of the purl stitches you encounter (the order in which you work the stitches stays the same). So for the wrong side of stockinette, where everything is a purl stitch, you do the opposite of normal Kitchener with 'purl, knit, knit, purl'. And when grafting a [K1,P1] segment, where the second and fourth stitches in the seaming order are purls, the sequence becomes 'knit, knit, purl, purl'. A [P1,K1] segment would therefore be 'purl, purl, knit, knit'.
It's hard to explain it succinctly in words, but the basic idea is to flip the parts of the base 'knit, purl, purl, knit' sequence that correspond to the purl stitches in the set of four stitches current being seamed. The challenge is that the seaming sequence needles to be adjusted as you work across the pattern. I find it helpful to work out the sequence for only the current four stitches, work the grafting, then repeat the process for the next set of four stitches.
It takes some mental effort, but being able to graft in a pattern is highly rewarding.