My tips comes from 3 librebooted X200s I’ve done (plus 1 fried due to user error by me):
your most important tool is a heatgun with smallest possible nossle (or is it nozzle?)
replace the stock WSON-8 nightmare chip with 8 mbit SOIC-8 chip
take a photo of red dot on the WSON-8 before heating it, it shows you the right position/angle/side for the SOIC-8 chip too
be aware that the whole bottom part (i.e. big area) of that nightmare WSON-8 stock chip is soldered
do not compile libreboot with raspberry pi nor any sbc you’re using (use real x86 computer)
when flashing, use slower spispeed than you’d use with Coreboot (older machine)
soldering the SOIC-8 chip do not require any skills nor good vision (super easy task)
With a good and especially small nossled heatgun you don’t need to cover the motherboard at all. If you melt the plastc top cover of the WSON-8, it doesn’t mind but not necessary either. Just don’t melt the motherboard (small nossle!!!) and you’re all good. Use tweezers rather than pliers, because force is bad and when the super-high quality soldering tin is melted completely, the WSON-8 chip comes off even if you just blow on it.
Flash the 8 mbit SOIC-8 before soldering it onto the motherboard.
I have no lots of soldering skills/experience, but it is fairly easy task if you just have the small nossled heatgun.
And oh yeah, some guides suggests to solder jumpwires onto the stock WSON-8 chip rather than heating it off, but that approach was way too hard for my soldering skills even with the smallest possible tip on my Pinecil soldering iron.