I saw this in a knit mag just tonight, had to get home to tell you!! You have your live stitches on your left needle like normal. Then you bring your cast on edge behind the needle (so on the far side of your needle). Put the left needle tip into the first cast on stitch(in the front of the cast on stitch, left to right), then put the right needle into the cast on stitch knit wise and knit it, pull both the cast on stitch and the "live" stitch off together!
I sure hope that makes sense!