They do not need soldering. Just got done replacing mine with this a few weeks back. Took me about 3 hours. I also purchased this set of tools as well: dealextreme.com/details.dx/sku.29544
They are invaluable, if I didn't have them I would have never got past the first couple steps.
I used this tutorial mostly (along with a couple others) to guide my way thru: formymobile.co.uk/xperiadisassembly.php
There are also many other ones if you google X1 disassembly. The only part I F-ed up on was during the removal of the metal trim ring that is glued to the old broken digitizer module. This is very thin. I bent mine in a couple of spots. Use a heat gun to warm it and it will slide right off.
Reassembly went OK. If I remember right something fell out and I couldn't figure out where it went but after looking at multiple guides I figured it out.
Mine works 100%, already ordered another one. I see they also have the actual LCD screen now too at Dealextreme.