Okay, let's see if I can remember.
Cast on the number of stitches that will make up your I-Cord onto a double-pointed needle. Knit all the stitches except the last one, which you slip as if to purl, pick up a stitch from your collar area and slip that last purled stitch over it. Slide the stitches to the other side and do that again (and again, etc.) until you have picked-up all the stitches around the edge that you want.
It's basically securing the I-cord to the edge.