Stevers,
You're not alone there. That cheap bag holds my jack and lug wrench and has two velcro straps that secure it. It is below and little left of the trunk release mechanism. Also, there are two foam blocks glued to the floor and the bag rests on one of them!?! What the other one is for is beyond my comprehension.
Also, I found one allen wrench sealed in a small bag down there. Any one know what it is for?