I recently installed Lubuntu from the latest alternative disk http://cdimage.ubuntu.com/precise/daily/current/ as a minimal install by installing it to command line.
Then I installed lubuntu-core
sudo apt-get install lubuntu-core
It then had none of the extra software install. Originally I tried with --no-install-recommends but this left it too bare and seemingly with missing dependencies.
After doing this
I installed lxappearance and obconf to allow me to change the themes easily
sudo apt-get install lxappearance obconf
I installed firefox without any recommended software as the addons are for Gnome.
sudo apt-get install firefox --no-install-recommends
I had some errors in my xsession-errors file that cleared up after installing the below
sudo apt-get install gtk2-engines-pixbuf
Network manager needs setting up after lubuntu-core has been installed from a minimal install https://help.ubuntu.com/community/Lubuntu/Documentation/MinimalInstall#Unmanaged_Wired_Network The nm-system-settings.conf is now called NetworkManager.conf as written below
Change Network Manager settings
Start an LXTerminal session, then issue:
sudo nano /etc/NetworkManager/NetworkManager.conf
In section [ifupdown] find the line managed=false and replace it with managed=true. Save and quit.
Get back to LXTerminal and issue:
sudo service network-manager restart
After a short while you should see "Connection established" message above the Network Manager applet tray icon.
openbox. This will create an "openbox" option inlightdm. Then just install the individual parts of LXDE, of which there are only a few and configure your openbox to use them. Then use the openbox session to use your LXDE-only setup. – Chan-Ho Suh Jan 15 at 5:01