Actually, I believe that the holes are pre-drilled (and threaded), and can be seen from the trunk. There are three points that you can choose from; one on each side and one in the middle.
According to the owner's manual, once you locate the attachment point that you want to use, simply use an awl or ice pick to make a hole through your rear shelf to mark the spot. Then use a razor blade to cut a 1" diameter hole around the hole you punched, and mount the hardware.
If you need to get the mounting hardware, apparently, you can get it from Acura.
The manual states that you can ask for it by writing to:
Acura Automobile Division
Customer Relations Office
American Honda Motor Co. Inc.
1919 Torrance Blvd.
Torrance, CA 90501-2746