I've never really needed to dependency inject into third party modules. If
I did, I'd rather fork the third party dependency than do some sort of
dynamic solution.

However, I do use dependency injection for (unit) testing my own stuff.
There are a ton of ways to do this but my favorite way of doing this is:

var fs = require('fs');
function Foo() { };
Foo._setBackend = function(backend) {
  fs = backend;

module.exports = Foo;

Then in the test setup:

before: function() {
  Foo._setBackend(require('./smart-fs'));

after: function() {
  Foo._setBackend(require('fs'));

The nice part is that the mechanism is trivial and doesn't depend on any
external modules or require() patching, without forcing me to make "fs" a
part of the interface/params to Foo(). It doesn't work on 3rd party
modules, but I haven't needed to do that thus far. Simplest thing that
works and all that..