Be very careful about how you do this. If you make any mistakes in your changes, you can make your system unusable (requiring reload). You also need to be fully aware of the security implications. It is highly possible to cause a security/login problem on your system(s).
If you want to just edit some resources, you can find an article
here[
^].
Some others that look interesting are
here[
^] and
here[
^] and
here[
^] .