Since I will be doing this replacement this weekend, and I had read all the horror stories, I was anxious last night to see what I was up against.
The stance of being on the passenger side with the right arm on the valve cover allowed me to get a wrench on the bolt and turn it a few degrees. But that was it for the combination wrench.
I found a 10mm ratcheting wrench I got at a sale and found that if I put it on I could get a few degrees rotation, but not enough to get it to "click". However, if I manually rotated the wrench three "clicks", I could go again, but that was too slow.
It did have the bolt loose now, which allowed me to see(rather feel) that the sensor was loose. The hole it fits into must be 1/64" larger than the sensor, which is great. What a relief!
So I hooked up a combination of extensions and a swivel joint on my 3/8" socket and snaked it down from the top. I guided the socket with the left hand, and loosened the bolt almost all the way.
I decided not to take the bolt or sensor completely out, since it would probably be easier to find the sensor hole and the bolt hole if I had just removed the old one.
You can barely see the bolt if you smash the left side of your head against the open hood.
To those of you who had trouble getting the old sensor out, I have a tremendous amount of respect for you. I can't imagine how you get down in there to remove the old sensor.
My hands don't fit, and they are "medium sized". I can put my thumb on top of the bolt, but I can't get a thumb and finger in there to turn or align the bolt. I see getting the bolt of the new sensor started as the "next great challenge".
Sorry for the long post, but I thank all those who wrote about this job before me, I think I read it all yesterday before I started, and it was the combination of everyone's experiences that helped me get started.