metadata.json

{
    "name": "test",
    "versions": [
        {
            "version": "1",
            "status": "active",
            "providers": [{
                "name": "virtualbox",
                "url": "file:///Users/erik/project/packer/vagrant.dev.1.box"
            }]
        },
        {
            "version": "2",
            "status": "active",
            "providers": [{
                "name": "virtualbox",
                "url": "file:///Users/erik/project/packer/vagrant.dev.2.box"
            }]
        }
    ]
}

shell output

me:project erik$ vagrant box add --name test packer/metadata.json
==> box: Loading metadata for box 'packer/metadata.json'
    box: URL: file:///Users/erik/project/packer/metadata.json
==> box: Adding box 'test' (v2) for provider: virtualbox
    box: Downloading: file:///Users/erik/project/packer/vagrant.dev.2.box
==> box: Successfully added box 'test' (v2) for 'virtualbox'!
me:project erik$ vagrant box list
test      (virtualbox, 1)
test      (virtualbox, 2)
precise64 (virtualbox, 0)
raring32  (virtualbox, 0)
raring64  (virtualbox, 0)
ubuntu    (virtualbox, 0)
me:project erik$ vagrant box update
==> default: Box 'test' not installed, can't check for updates.
me:project erik$ vagrant box outdated
me:project erik$

Vagrantfile

# -*- mode: ruby -*-
# vi: set ft=ruby :

dir = File.dirname(__FILE__)

Vagrant.configure("2") do |config|
  config.vm.box = "test"
  config.vm.box_version = "1"
  config.vm.box_url = "file://" + dir + "/packer/metadata.json"
end