[Zope] Passing arguments when calling precondition

Could anybody tell me a reliable method on how to pass arguments for a script/method employed as precondition for some File objects? What I'd like to do is to pass a record identifier to the method called as precondition, increase a download counter in a database, then let the visitor download the given file. If the record identifier would be None, an exception could be thrown, thus denying access to the file. In this case I wouldn't bother with users who try to enter absolute URL with a valid record identifier known e.g. by accident for the files requiring registration before downloading, since the download counter would work and that's all what I want. e-Musty