1st cast on using the provisional co for toe up socks. For this sample I'll be making a 3 stitch garter tab. So I have 3 stitches on each needle.
Just pull the needle through the 3 you won't be knitting right now so they are further down the cable and out of the way.
With the 3 stitches that are on the needle
kfb, k2 turn
kfb, k2 turn
repeat these steps. the 1st stitch of the kfb will be the one that you would have to pick up later. Were just doing it right now. End on a kfb row. Do these steps untill you have enough stitches to equal what you would be picking up later.
You can see the 3 loops on the cabel thsn 5 stitches created by the kfb and the last 3 are the live stitches
Now pull your cable tight causing the 3 stitches from the co to pop back up to the tab. My tail is kinda in the way here, but I've moved the cable through so all the stitches atr together.
turn your work and knit across all stitches. this is the 3 live stitches, however many you have on the side (i have 5 in my sample) and the 3 from the co end.
you have just made a garter tab and didn't have to pick up a single stitch!
Here is the co to my current shawl that I used this technique for. This called for a 2 stitch garter tab and 5 stitches to pickup along the edge as well as another 2 stitches from the start.