My rear speakers have two holes in the back which I hang them with using screws into wall anchors on my side walls.

But now I want to put them in the corner so they look like the pic below. But I can't simply drill into because now I'm at angle. Any advice?

(didn't get any responses in Speaker forum and you guys - and McCall - are the experts in all things handy)

http://i11.photobucket.com/albums/a162/vinnyanddaisy/newsetup.jpg

edit: ugh, typo in title

Anchor a piece of wood between the two walls at each corner. That will give you the backing for you to put a screw for your speaker.

Assuming that is a 5.1 placement, you have them in the wrong place anyway. they should be more next too, perhaps slightly toward rear, and facing [from the sides] the seating. Angled in the corners is not the best choice.

http://www.dolby.com/consumer/home_entertainment/roomlayout2.html

Putting some wood backing behind it is the best way to do it. McCall is right though, if it is for 5.1 it won't sound right having them in the corners (assuming they are directional speakers). If they are true surrounds then you would probably want them directly on the wall so they can use your side walls to bounce the sound. By the looks of your drawing though, you have directionals.