Installing Node Modules in a Standalone Environment

I'm working with NodeJS in a small standalone isolated environment, as such commands like npm install -g can't reach out to the internet for dependencies. To "workaround" this constraint, I'm doing installs on a regular system and just air-gaping the pieces over.

Any given module (and all its dependencies) lives in /usr/local/lib/node_modules/XXXXX, and if I'm actually in that directory and enter node cli.js, it works.

However, back on the main system invoking module XXXXX by name from the command line runs that particular module. The isolated system does not, and I'm trying to find that last little step of how npm is wiring things up.

What's the pedantic methodology once one's this far to teach npm (or node) of the new command?
I'm willing to resort to hacks or aliases if absolutely necessary, but I'd like to do it the npm way.

Unfortunately, I'm not at liberty to set up a CouchDB or such and run a mirrored repository — I'm working in a tight footprint that's trying to keep things small and sleek.