Install VirtualBox v5.0.26 from here: https://www.virtualbox.org/wiki/Download_Old_Builds_5_0
Install vagrant v1.8.4 from here: https://releases.hashicorp.com/vagrant/1.8.4/ (1.8.5 seems to be current, but there’s a documented bug around ssh auth).
Install vagrant-hostmanager plugin.
vagrant plugin install vagrant-hostmanager.
hub clone dcos/dcos-vagrant cd dcos-vagrant
VagrantConfig.yaml from the example.
Download the DCOS v1.8.0 installer script from DCOS (in the dcos-vagrant directory).
Copy the right one of the versioned config files into the right place.
Start up the guests (from the documented "minimal" configuration, with 1 each of master, agent-private, and boot nodes).
vagrant up m1 a1 boot