require a file outside of node_modules with grunt

I am trying to require a node module that is used in my app into my gruntfile.js but whatever I do i get : Cannot find module 'appjs/config

In the gruntfile I simply do : var myconfig = require('appjs/config');

But it just don't want to load, is there a way to import this files easily? I also tried various path but appjs is at the root where the gruntfile is.