When you want to adjust an existing package, you shouldn't try to overwrite the original files. Think about it, once the package updates to a newer version, your changes will be gone.
Instead, Sublime Text offers different ways to customize packages – as mentioned in the Package Control documentation:
If a package for Sublime Text 3 is installed as a packed package, it
should be possible to directly override individual non-python files.
To do this, create a Packages/{Package Name}/ folder and save
customized versions of the files with the same name they are in the
.sublime-package file.
As mentioned by MattDMo, you can also create by additional build systems by saving the to Packages/User
. You will then be able to select them from the build menu.
On a side note, make sure that your .sublime-build
file is valid JSON – the enter code here
part in your example makes it invalid!