I had my first taste of success last night, and it was delicious!
I aimed the dish for AMC 9, without any sort of meter reading visible from the dish. I went inside and did a scan in MyTheatre -- locked (!)... getting info (!!)... lo and behold, 2 channels found!!! No TV channel has ever looked so sweet as those first few seconds of PBS HD free to air.
Confused as to why I was seeing PBS at all when pointing at AMC 9, I searched around until I eventually realized I was looking at AMC 3. Oops. Well, at least AMC 3 has a few more channels, and once I did a bit more scanning, I also had Muslim Television Ahmadiyya in all its glory.
With my current setup of only a PC tuner, I think I was lucky to find anything. I don't want to shell out for a STB just to get the thing aimed, so maybe I'll see if a sat finder can do the trick.
Since I'm pointing through a narrow opening in the tree cover, I'll have to move the dish to hit anything else. Not a big deal, since it's only bolted to a quarter sheet of plywood, but it means I'll have to give up my PBS HD on AMC 3. I'm not sure I'll be able to see much else I'm interested in, but now that I'm hooked, I want to find as many channels as possible!