user-defined variables in logon script

I need some environment variables set when a user login to a domain. These variables are used on the client size, both by NT client and some scripts. Some of the environment vars include the port number, the server's name.

I wonder if I can use the command "set" to set these environment variables on the logon script. For instance, in my login.bat file, I put "set portNumber=5001" to set it. The logon script is located on the server.

Or how can I set these environment variables whena user logs in?

Thanks.