The way you phrase your question seems to indicate you realize you would have to replace the entire board. For the benefit of others, let us make it clear that you cannot
upgrade the processor alone on x60/x61 series laptops, or x60/ x61 tablets either. The CPU is soldered onto the system board. Some interesting discussion here about upgrading X6x machines in general: viewtopic.php?f=30&t=91218
I think it's probably easier/ safer to remove the LCD assembly first, as you will be disconnecting all of the wifi wires anyway, and it will just be in your way. If you do, be careful
when lifting loose the (exposed) right side of the LCD cable which is attached by that piece of black tape you see in picture #4. The top, right portion closest to the screen can tear away easily.
As someone who has torn down and reassembled dozens of these, let me humbly say that overall the guide is not bad... for a bunch of amateurs LOL. Bad grammar is a pet peeve of mine, so the spelling mistakes and poor sentence structure are difficult to bear. Then again, an expert English teacher such as myself notices these things more easily I guess. Alas, spelling and grammar are a lost art on the Internet and on this Forum also
... This Guide was probably prepared by someone who is not a native English speaker, so we will be merciful.
I had a quick scan, so I can't say every single part is technically correct, but that Guide should help you get the job done of changing out the entire board, or just changing the fan/heatsink or renewing the thermal paste.
A couple of other points (I'm sure you realize these things, but for the benefit of others who may read this thread): It is wise to first touch something made of metal to discharge static electricity from your body before working with sensitive electronic devices. Some people prefer to wear an anti-static wrist strap and ground themselves. I would also remove the RAM modules and hard drive before even beginning. They are delicate, and can easily be damaged in all of the "deconstruction." Put them safely in a small, padded anti-static bag. Also, keep all screws in a small container so they don't run away, which they love to do. It might also be prudent to wrap a thin plastic film over the face of the LCD as all the pulling and twisting and resulting sharp, exposed metal pieces could accidentally scratch the LCD, especially if it's your first time breaking down one of these.
Make sure you have the proper size screwdriver, as some of the fans on the x6x machines are held in place by screws that are a bit tricky to loosen.
If you want to renew the thermal paste, follow the rice-grain size credit card advice you'll find posted elsewhere on the Forum. Also, be sure to use a good quality, highly conductive thermal compound such as Arctic Silver 5. Do not
use toothpaste, chocolate syrup or any such concoction as some were joking about in a recent thread here on the Forum
Have a great day,