Unity Editor script in DLL

Hi, I'm am trying to create a dll (or any script) that doesn't depend on the project's compilation. We have a file that has some constants which need to be auto-generated by our build script. The file is in gitignore, so when you pull the project, the menu that the build script adds (with the option to generate the constants file) doesn't exist, because you are missing the file :) So the project doesn't compile, because it requires a file to be generated, but the option that generates the file, doesn't exist because the project doesn't compile :) Is there any way to add a menu item that doesn't depend on the project compilation ? Thanks