I need help starting Gnome3 in runlevel 3

[John Wendel]

I like starting by box in runlevel 3 and using startx to get the desktop 
running. I created .xinitrc with the contents being "exec 
gnome-session"; the desktop starts, but gnome-shell loops consuming 145% 
of 2 cpus. Needless to say, the system isn't very usable.

If I run init 5, and go thru gdm, the desktop runs fine, but I'm trying 
to eliminate unnecessary processes, and I really don't want to run gdm.

Can someone share the spell that will get Gnome running correctly using 
startx?

Thanks,

John