x94,
I wouldn't worry too much about having the M22s on bookshelves as long as you have a small amount of flexiblity on where you place the M22s. Ideally, you want your M22s at least a few inches away from the wall since they are ported and you don't want the air from the port to be distorted by the back wall. Also, you want to keep the tweeters at or near ear level.
My current setup has my M22s on a long, low entertainment center. It's a pretty old piece of furniture that was designed to hold a stereo, record player, and records -- but I've made it work for me. Here's a pic I took of it earlier this year. I have some room on either end of the EC to move my speakers forward and backward and closer together or further apart.
