Yeah that's all we can do at the moment. But "John Smith" is a whole lot easier to read and act on than F4J5T6KP. Is that what you are talking about? The windows network identification id? The word "custom" threw me a bit.
When you build your connection string, one of the parameters you can include is "workstation id". You can set it to anything you want, so you could dynamically assign in the user's actual login name from NT. And then in SQL Server, you can use the HOST_NAME() function to retrieve it. Unfortunately, if somebody connects to your database directly or from some other application, then the workstation id will just reflect its default settings, which I think is the PC name.