There is no deb or rpm file available yet but it runs out of the box once you unpack the tar file. To make it available as a global place the unpacked folder (you don't have to do this but I renamed the folder firefoxDM to differentiate the the two versions of Firefox) somewhere in your available executable paths. (I went with /usr/share/) I then used my menu editor to create the entry so it appeared in my menu. For me the full path to the executable is /usr/share/firefoxDM/firefox
I also grabbed a Icon to make the difference between the standard browser and the developer edition visibly apparent.
Yes its that simple to setup. Enjoy