Check out these videos from LE55ONS. The first shows a step by step dissection of the Nokia Lumia 1020, disassembly and then reassembly with instructions on screen replacement. The second is a screen frame exchange.
As per usual, doing this voids your warranty so do this at your own risk.
Even if you’re not going to do this, it’s always an interesting watch to see the internals of these Nokias.