The Truth About Guns reviews the Zack holster from Dale Fricke, and it's very informative, including a short video of it in action. There is some hate for the concept in comments, as well as some hate for AIWB in general.
I didn't try carrying with the Zack anywhere else on the waistband other than in the front, and I also didn't try canting the weapon. One thing I noted in comments was that the gun carries better if you adjust the slack out of the cord so that it takes the weight of the gun and keeps the trigger guard area off the belt.
I also added in my thoughts on the best part of using the Zack for AIWB: you don't have to holster a loaded pistol down into your pants -- that being the most dangerous part of AIWB carry. You will notice that he snaps the Zack onto the Glock while it is out of the waistband, and then tucks it in.