Basically you treat the circulars just like straight needles, just not joining the last two cast-ons to make a circle.
So, cast on. Then follow the pattern. When you get to the end of a row, you just switch hands for your needles. The cord on the circulars helps with all of the stitches.
Good luck. It's a fun scarf. I'm making one now, but I'm using the short-row method from the Scarf Style book. It's probably the same amount of stitches in the end though.