Earlier this week it wasn't possible yet, because Cinnamon is built for Clutter 1.8x and Ubuntu 12.04 has switched to Clutter 1.9x. Clem has indicated that it is already fixed but will take some finishing up before it becomes available. See here (especially the comments at the end): http://www.ubuntugeek.com/how-to-instal ... 11-10.html
Edit: Perhaps as zerozero says this is already done
I guess there is no harm in trying to install it; you can always select to run a Unity session from the login screen instead of a Cinnamon session.