I don’t know of any special training method to help you deal with lower O2 concentrations other than the ones we talk so much about in our book and on this website. Get as fit as aerobically as possible and you will have your best chance of success.
We have worked very closely with some top alpinists and can tell you when it comes to guys like Steve, David Goettler, Ueli and Kilian that the one ingredient of training they all share is to train a hell of a lot (as much as their bodies can handle) in the aerobic range. This means massive volumes of distance and vertical. That HAS to be the biggest part of the training program for success on 8000m peaks. If you are not doing that then trying things like deep diving or sleeping in an artificial hypoxic tent or any other ‘magic’ is not going to help you. If you are training 20 hours a week with at least 5000m of vertical each week and you have the time energy to try these other things then for sure, give them a shot. They might add a few percentage points to your performance but with out that training base you will be fooling yourself.