Have a look at the files in
There you'll find
ubuntu-2d.desktop (if you're not on 12.10 already) and
gnome-fallback.desktop (maybe also
gnome-classic.desktop. I have gnome-shell installed maybe that's where this is from).
Open one of those and you'll see they all have an
Exec=gnome-session --session=... line. For gnome-fallback open
Now you can
/usr/share/gnome-session/sessions/gnome-fallback.session the line
RequiredComponents=gnome-panel;gnome-settings-daemon;cairo-dock; (check the executable name!)
Exec= line, for example
or also copy your current autostart folder
.config/autostart/ to a new place
Exec=gnome-session --session=gnome-fallback -a <Newplaceofautostartfolder>
create a all new session. copy and rename both
gnome-fallback.session to their new to their respective places under a new name and adjust your new session like in 1.
The first two of those work but have the disadvantage that they may or may not be overwritten on update (you will have to check, I'm not sure).
In 2. Also if you copy your autostart folder only one of those will be updated depending on which session you are logged into.
So I recommend doing it as shown in 3. Have fun.