Congrats on the Heli Pro, it is a nice bag.
If you take the mouth piece/valve off, you can snake the tube though the shoulder strap then pop the valve back on. (Edit section, it won't close with the bite valve in the shoulder, atleast with my experience. You can find different styles at the store, REI, etc. that may work. I just shove it back up in the shoulder strap.)
Heads up; you may want to have a bottle for back up in the back country. I quit using bladders with winter activities, they always freeze no matter what I try even with insulation.
Edit: misread question.
Last edited by Lamb; 11-15-2013 at 03:06 PM.