Many people advise to use 2-4 less stitches to make up for the ones you'd use for seaming. Knit to the underarm, then divide for the front and back and knit them back and forth separately. Depending on what kind of shaping you want, you can pick up stitches for the sleeves around the armhole which results in a drop shoulder sleeve. You can knit to the underarm on both the body and sleeves and then join them for a yoke top (with raglan shaping, or just decreases). Putting in a standard set in sleeve is doable through picking up stitches, but you will be doing short row shaping to mimic the sleeve cap shaping.
sue- knitting heretic