GeoIP for Intranet

Hi everybody,
I have installed Pikwik in an intranet and I would like to track the location (country, offices) of users.
I have the map of the IP in the MaxMind csv format (for Countries or Cities), how can I implement this?
Do I have to convert the csv in dat file? How?
Or is there any external plugin to do this?

Any help is welcome.

Thank you,

Giorgio