First integration into another project:
git remote add -f CMake https://github.com/Eyescale/CMake.git
git read-tree --prefix=CMake -u CMake/master
git commit -am 'Merging CMake subtree'
Setup for new clone of a project:
git remote add -f CMake https://github.com/Eyescale/CMake.git
Update:
git pull -s subtree CMake master
git push
[fork repository]
git clone https://github.com/<fork>/CMake.git
[change]
git commit ...
git push
[open pull request]