ok I have find a way to "untick" the auto connect option using GConf, but I cannot seem to "tick" it back.
when I set the auto_connect to "[]" it works:

gconftool-2 -g /system/osso/connectivity/network_type/auto_connect
[]

but when I set it to"[*]" it doesn't ..
gconftool-2 -g /system/osso/connectivity/network_type/auto_connect[*]

any idea?