I'm only about 20 rows in, so I can't tell how well it's working, but this is how I'm planning to reduce the sleeve circumference. The XL size has 65 stitches in the sleeve at the point where you divide sleeves and body. At 4 st to the inch, this is about 16". I want more like 14", which is the arm size of the next size down (57 stiches). So I need 8 stitches fewer in each arm section. Each increase row as written increases the size of the sleeve by 2 stitches, so I need to miss out the increases on the sleeve side of the raglan line 4 times. (That is, the increases after the first marker, before the second marker, after the third marker and before the fourth marker). I'm distributing the rows with fewer increases evenly down the yoke, about one every 16 rows.
I think it'll work.