Go to your local mountaineering store (or some other venue that sells it) and buy yourself some stretchy cord like small diameter bungy cord and feed it through the slots on the crampon patch, add one of those depression-clips and voila, you have an adjustable attachment point for your crampons on the outside of your pack. Beware of bushwacking with this in place lest you get snagged by a tree and that bungy bites into the back of your head.
Or buy a pack with a crampon pouch. I'll take the extra ounce for the convenience it provides.