NT4 Roaming Users

We have roaming users in a domain. As each user roams from site to site we need to map a local share (at that site) to G:\. How do we do get the script to run, identify the site that they are at, then enter that server name into the logon script so that always map a drive to the local server share at the site that they are logining in at.

Solution has to be centrally managed or we would have local logon scripts.