Is it possible to land a commercial aircraft with an elevator trim stuck at a high degree?
From the Boeing 737 emergency procedures:

After all attempts fail to free the stabilizer...


  
  Anticipate higher than normal elevator forces during approach and landing.
  The thrust reduction at flare will cause a nose down pitch.
  Note: Elevator control is sufficient to safely land the airplane regardless of stabilizer position.
  




Note on terminology: Most jet-liners (including the 777 and 737 as the question requests) use a trimmable horizontal stabilizer (THS), in which the pitch trim is achieved by positioning the whole rear wing up/down -- as opposed to using trim tabs.


(airteamimages.com) THS of an Embraer ERJ-190.