Actually according to UEFA Stadium Regulations 2006 Article 16.  Point 2 reads: 
  
The use of temporary stands is prohibited. 
  
Although point 1 of the same article would put our O'Donnell Stand (North and South) out of use as it reads: 
  
Seats for spectators must be individual, fixed (e.g. to the floor), separated from one 
another, shaped, numbered, made of an unbreakable and non-flammable material 
and have a backrest of a minimum height of 30 cm when measured from the seat 
  
Although again same Article, if I read this right Terracing is allowed in the First Qualifying Round...  Unless they have changed where it says Round 2, now reads round 1.