I ordered winter tires and steel wheels from Tire Rack. They shipped the same day I ordered and the tires and wheels showed up in only two days. However, I have not installed them yet. (For reference, I got Pirelli Winter Carving tires on 16" steel wheels with hub caps for a total of $699 USD including $91 shipping, mount/balance included.)
I asked the Tire Rack rep how the wheel centering on these steel wheels compares to the OEM method. He said their steel wheels have the exact same 67mm hub-centric mounting method as the stock wheels. The standard lug nuts are used with the steel wheels and there are no adapters/spacers/etc. It's a proven bolt-on just as good as OEM, according to them.
I'll install the winter tires by the end of this weekend and will report back if I learn something that doesn't match what I was told. Scratch that, I'll take pics and will write an update no matter what I find out.
Jon