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You are correct, it won't work unless the wacom.ko driver is loaded. Usually sudo depmod -a or rebuild all module dependencies prevents that. Sometimes it takes a few restarts to shake out. And for whatever reason some systems just won't auto-load the wacom module. To "force" it to load add wacom to the bottom of the list in the modules file in /etc.
and restart.Code:gksudo gedit /etc/modules