On the back of the sweater, I blindly followed the directions to cast on 150, then increase 6 on each side after 9 rows. This made a stairstep instead of a nice curve. I will have to figure out what to do with this when attaching the trim.
On the front, I got smarter. I cast on the waste yarn over the number of needles required for the widest part of the garment. Knitted one row with ravel cord. Then pulled the end needles (about 20 each side) to hold, set the machine for hold, and pulled out two needles each side for several rows until I got to the widest part of the garment at row 17. I also decided that decreasing four stitches each side was not enough shaping for me to worry about and knitted straight from this point up to the underarm.