How do I execute build commands using files from a different directory?

If your script command uses files that are in a different directory you can simply cd to the directory first, then run the commands.

An example would be:

cd /path/to/folder
npm install

If your script is within the repository then you can use the project golden parameters and then run the command.

An example would be:

cd %base_path%/custom-directory
npm install