Yes. Cast sts on to the left needle, work those st across, then turn, cast on the next set of sts to the left needle, work them all the way across and continue with the pattern. This is a very good looking jacket and looks like lots of fun to knit.
Go all the way across the row. You're working from the top of one sleeve. The first cast on sts are possibly for the back and the second cast on st are for the front (or vice versa) so you want the two cast on rows to be on either side of the arm.