I was wondering, if it is possible to customize just a single file which lives inside a resource directory (from an other package). I heard of z3c.jbot, but this seems to work for files inside CMF Skin Folders. Nevertheless, I tried it with jbot yesterday, but there was no avail.
Sure I can. To give you some background. I intend to modify a javascript file of collective.ckeditor living in src/collective/ckeditor/browser/ckeditor/lang. If you want to verify this path, please look into the release version on Pypi.
Now I do the following steps:
Create folder overrides/lang relative of my product root.
That's due to the setup of collective.ckeditor. The version on Github can be used to create releases, which will populate the folder /browser/ckeditor with the original files.
If you look into the zip file provided on Pypi, you will see the directory and files there. It's the very same directory specified in collective/ckeditor/browser/configure.zcml: