This is a free tutorial.

This technique is essentially the same concept as an afterthought heel, thumb or pocket. The biggest difference is that the placement of the stitches to be held is planned in advance; thus the stitches that need to remain live are held on waste yarn (instead of having to cut your fabric to remove a small portion of your row and then weave in those bits). This method can be used for heels, thumbs, pockets or any other application you can imagine (like the neck of a poncho or sweater!).

This technique is very simple to do and produces wonderful results when done properly. I have attempted to offer the clearest set of instructions possible.