Tried shortly with a fresh SP2010 install but couldn't find a way to do this...
Is it possible to configure the usage reporting or the Web Analytics feature to log usage information anonymously?
State regulations require that one cannot log complete user information, so one would have to alter e.g. the IP address to be 127.0.X.X instead of 127.0.0.1 or something along those lines.
Would a custom usage receiver do the trick? Can I turn of all other usage receivers then to only collect the data I'm allowed to?