Hi bErEsTh,
Since no one has replied...
I don't believe you can do this, if the file is on the server, your IS department might have a utility which can track a files usage - if I remember right though this carries quite a bit of overhead, and they are usually reluctant to do this.
The other option might be in the express tools if you have them. Back in the days when AutoCAD used to create lock file, (*.dwk), there is (or was?) an express tool that could tell you who was in a particular drawing ("Who has" I think was the name of this express tool) but I don't know whether or not it tracked any kind of time information.
Sorry if that's no help...
Todd