There are several videos on Youtube where people have filmed their monitors
while installing Libreboot on Thinkpads (X60 and others). You should, of
course, get familiar with the documentation on Libreboot's website as well.
One thing to consider is that it's possible that a X60 with Libreboot
installed won't boot distros that don't have the libre kernel.
So you should either
- start flashing Libreboot with Trisquel or Parabola installed
- have a USB drive with Trisquel available
Because if you start flashing Libreboot with e.g. Debian installed, you could
run into a problem at the point where you have to restart the machine to
finish the Libreboot flashing (if you're unlucky, Debian won't start anymore
and you're not able to finish the Libreboot flashing, unless you can start a
Trisquel live session).
I'm not saying that this will happen, but there are some reports.