Just guessing here... Not sure if this will work but from looking at "gconftool2 --help" this should not only set the theme, but also do ALL settings. So, modify one users settings so they are exactally how you want everyone's to be and then:
Code:
gconftool-2 --dump / > global.xml
Then try to load it up somehow globally when ever a user logs in. Maybe inside a global Xsession file or the Global xinitrc file?
Code:
gconftool-2 --load=/path/to/global.xml