You could always put 1 big nail right through the middle of the speaker. (just kidding).
I certainly hope you're kidding!
You should only use screws in the ceiling.
Perhaps what you could do is remove the mounting clips from the back of the surround and utilize the same screw holes to attach a small wooden plaque or wooden bar to the back of the QS8 securely, then put a couple of screws through the plaque or bar into the ceiling. Just leave a small opening or cutout if you use the plaque method to attach the cables.
