NodeConcat is available through NPM. If you want to use it, you should install it locally so that you can use the module as a command line utility from any directory.
npm install concat -g
Next, you will need to create a manifest file. The manifest file should list the paths to all the files you want to concatenate. These paths should be relative to the directory root. If you include directories in this list, all files inside the directory will be recursively included. Here's an example of the contents of a manifest file.
lib src/helpers.js src
Finally, run NodeConcat from your command line. It requires two arguments: (1) path to manifest and (2) path to output.
concat manifest.txt app.js
You should note that NodeConcat runs in asynchronous mode by default. That means that the output may not be in the same order as the input. If you want to garauntee that the output is the same order as the files specified in the manifest, you will need to pass the sync flag as a third argument.
concat manifest.txt app.js --sync
More information on NodeConcat is available at http://knicklabs.github.com/NodeConcat/.