I'm in the final stages of knitting a cardigan in a simple pattern stitch.
Start by turning the garment inside out. You will notice that this beautiful stitch happens to produce a reversible basket stitch on the inside. Now follow steps One and Two from my earlier grafting tutorial. (Hint: open it up in a separate window, so you can see both tutorials.)
Step One: The stitches are transferred to dpns. It doesn't matter if the sleeve is above or below.
Step Two: Remember to pay special attention to the orientation of the extra stitches picked up on the end of each needle.
Now, instead of grafting, simply unite the gap with a 3-needle bind off. It will look like this from the wrong (working) side,
and like this from the right side. Notice how beautifully the vertical lines of the stitch pattern come together.
It's not the first time I've done underarms this way; I used the same method of closure a couple of years ago when I made this unpublished aran.
OK, now back to that shawl collar...