I would suggest you practice close to home first. Learn the bow drill, cordage, flintknapping, primitive shelters, simple bow and arrow, dead falls, snares, fishing. Then there's edible plant identification. If you want to keep it simple, eat spruce buds and the soft bark. You don't really need food if your only trying to make it two or three days. For water, there's enough in the air if you know what your doing.
Check out John and Geri McPherson's books.
But if you are hell bent, even with a group, consider taking along one of these if you are out of cell range:
http://www.mec.ca/AST/ShopMEC/Paddli...tor-beacon.jsp