You can do it [https://trisquel.info/en/wiki/installation-guide here.] To
write a manual you don't need any special privileges.
The only reason I have not written a dual-boot guide is I don't have a copy
of windows to use as an example. And just FYI for anyone wondering a manual
on how to dual-boot trisquel and windows would NOT violate the
[https://www.gnu.org/distros/free-system-distribution-guidelines.html GFSD]
(see the section on documentation) because that manual would help people move
from a non-free OS to a free one.
If you are going to write such a manual I would ask that you maybe take a
look at some of the other installation manuals such as
[https://trisquel.info/en/wiki/trisquel-installation-50 this one] and maybe
try to keep the same style as much as you can. If we have tons of different
styles all over the wiki it can make the documentation look a little weird.