Much to my dismay I showed up a day after the scaffolding was taken down in this livingroom that had 40 foot ceilings, and I needed to install 4 ceiling speakers.... (damn)...
I wasn't about to use a lift (hallway too narrow), and sure as hell didn't want to haul in a bunch of scaffolding, besides I hate heights! LOL!

...So I thought about it for a second then here is what I ended up doing... I went up into the attic, lowered some speaker wire down through each cut out, and secured a speaker to each wire, and pulled the speakers up (from the attic)... and then adjusted the dog-legs over the sheet rock, Because I had to install them with the grilles already on) and installed wood shims under the dog legs to tighten things up, and then siliconed them.

They, uh, are still up there!