Pointing to a custom npm package version, two levels deep?

When pointing to a different location of a package my app needs, I can usually just replace the version with "depName": "githubUser/repoName" and it works great.

But what should I do if the package I need to customize is itself a node module of some other package? e.g.

myapp
|_
  express.js
  |_
    send.js

I prefer to avoid publishing a fork of the first package, express in this example, just to use a modified version of send.