/usr/sbin/update-alternatives --install /usr/lib/X11/displaymanagers/default-displaymanager default-displaymanager /usr/lib/X11/displaymanagers/tdm 15 /usr/sbin/update-alternatives --config default-displaymanager

Above sets the default display manager to TDM. What is the corresponding first command to install TDE (as a desktop selection)? I know how to make it work via symlink, but what is the update-alternatives command method??? The symlink method doesn't make TDE an available selection when update-alternatives --config is run.