The exactly same way you would with straight needles. It'll make better sense once you actually have the stitches on the needles, but all you do is knit up one side, turn it around and go back. There really is no difference.
OTN: Jeckyl and Hyde Hat, Shetland Shortwrap( )
FO: Lacey Stole, Library Capelet, Dead Fish Hat, Tree Bark Scarf