I guess you did not read my previous answer the net of which is: you can't.  Sky+ needs two feeds from the LNB (Dish).  None odf the other socket will work.  The ONLY way you can get Sky+ to work properly is to ask the management company for your flat to provide another feed.
I just thought, before you ask, you cannot split the existing  feed in to two.  They have to be individual wires from the LNB.
                
 t
                
 August 2007