When I used it in my hermits tank, I had a suction cup with a hook on it and I would put the hook through the holes in the wood to keep it up. Sometimes the section cups fall down though, so it might be a good idea to tape the suction cups on to the glass.
I have this HUGE piece of it that is "Y" shaped, and its pretty neat! But the holes in the middle of it are probably big enough for Wink to get into, so I wont give it to him untill he is bigger.