Install Vagrant from source.
The github repo is here: https://github.com/mitchellh/vagrant
And these instructions should allow you to build and install the bleeding edge version: https://github.com/mitchellh/vagrant/wiki/Installing-Vagrant-from-source
If you want the latest stable version then once you have cloned the repo as described in the link above you should checkout the 1.2.2 tag with git checkout v1.2.2
and then build that.