I also am confused about getting O2 into the solution (by aeration stone as the only way to achieve sufficient PPM)...isn't the yeast able to scavenge O2 from the foam that is at the top of the wort after swirling/stirring/etc... That foam is pretty full of bubbles or at least it looks like a ready source of O2 that the yeast could access.
Remember that air is only ~20% oxygen. Yes, the foam is a good source but there is a limited quantity there, and most of the yeast is in the liquid and not the foam. If you shook it over and over again every hour or so after pitching, allowing the yeast to consume the dissolved oxygen between shakings, you might eventually be able to get as much as through direct oxygenation. That is a lot of work, though, and all the splashing and foaming will only reduce the ability of foam positive compounds to form a head on your finished beer. They can only make foam once.