I managed to get my pal's Oculus Rift hooked up to my main machine properly, and after screwing around with some demos briefly, I decided to hook it up to the Main Event.
First, thanks to Sharaleo for pointing me to the place that I would have had to have dug up myself -- your post probably saved me a half hour of messing around at a minimum.
Second, holy galloping crap! That was quite an experience. I didn't screw with all the options that they recommended since I was in a hurry to get cracking, so much of the text was unreadable using the Rift, but the feeling of being in the cab of the truck was amazing: looking to the side as I turned, turning my head to look at the side-view mirrors, it was an incredible (and also vaguely dizzying) time. I can't say it was quite as much fun as "normal" ETS since it was blurry enough to take away the joy of the scenery, but you can certainly see that in a couple years this will be THE way to play any and all simulation games.