bundle.js

#!/usr/bin/env node

var exec = require('child_process').exec,
  sys = require('sys'),
  fs = require('fs'),
  p = JSON.parse(fs.readFileSync('./package.json').toString()),
  libs = ""

for (prop in p.dependencies) {
  libs += prop + '@"' + p.dependencies[prop] + '" '
}

sys.puts("Installing libs... " + libs)

exec('npm install ' + libs, function (error) {
  if (error) {
    sys.puts(error.message)
    process.exit(1)
  } else {
    sys.puts('ok')
  }
});

package.json

{
  "dependencies": {
    "connect": "0.2.1",
    "express": "latest"
  }
}