The minimal shaft mobility quickly causes blisters and pressure points, which is why we strongly recommend wearing silk stockings under ski socks. But even this will not work for long. Touring ski boots and many freeride boots have a hiking mechanism to unlock the shaft for the ascent. This allows an ergonomic movement, larger steps can be taken (= higher walking speed) and the effort per step is significantly reduced. Further differences are described under “What distinguishes a touring boot from a normal ski boot?”
Nothing is impossible, assuming that the alpine ski boot fits the touring binding (this only works with so-called frame bindings).