Do like I did a few years ago.
When the installer showed up, I informed him that I would be doing the actual receiver swap/install because I knew were all the cables where and went, and he didn't. I told him he was perfectly welcome to watch me so that he knew "I was doing it correctly". After about two minutes of watching me fiddle with cables, the installer announced he'd be back in a bit and left in he's truck. About an hour later (long after I had the receiver installed, activated and watched a half hour program), the installer came back. I signed the papers at the door and he left. He seemed to have no interest in inspecting the install (didn't even peek in to see if the receiver was working). I think its likely they're use to this kind of situation.