How do I test unity 8 in 15.10?

I have a 15.10 installed on a machine since the beta release. Today (official release of 15.10) I did an update. I thought I would have been able to test unity 8.

But the greeter is the same and I don't know how to launch the unity 8 session.

Old questions about unity 8 are not an option, since today Canonical says that "In 15.10, Unity8 is demonstrating Canonical’s convergence vision as a tech preview. Users can log into a Unity8 session on the desktop, experience the new features, and cleanly revert to the default Unity7 experience."

Solution 1:

Im pretty sure you can install it with sudo apt-get install unity8, whether you can easily swap between it is another thing entierly