I went with a decidedly unscientific method off adding a sleeve to my Countour pack. Just above the shoulder strap connects to the pack, I cut a 1/2" hole to slide the tube through. I burned the edges to eliminate any chance of the hole spreading. It's never spread, and it's so small that while it could conceivably leak, I haven't seen it (and would be covered by a packcover anyway). I sometimes let it hang loose, or attach it by looping through a loop that is on the strap shoulder.
I always pack my backpack with a 1/3 piece of Ridgerest against my back insdie the pack (to eliminate stray pot handles from stabbing me), and slip my Camelpack against that. My Camelpack is a 70-ounce bladder that is actually a little backpack.
You have to pack the bottom of your pack, first, to allow the bladder to stand on top of the gear you pack (mostly, because the tube isn't long enough).