This is for the client install btw. It was pretty easy and I wasted some time figuring it out. Just do a setup /? and it gives you all the command line options but I would recommend that you install the prerequisites first which are Windows Installer 4.5 and MSXML 6 SP1.
The cmd line I used is:
setup.exe /silent /lang=ENG LFCADDLOCAL="ALL" LFSSADDLOCAL="ALL" LFPDADDLOCAL="ALL" LFSCADDLOCAL="ALL" DESKTOPSHORTCUTS=0