Last login date for network home users?

I want to prune old users from my 10.4 server. Is there a command or a script that will show me the last time one of the network home users logged into their account? I've found that the terminal command 'last' will only give me the user data for the server. So I can see the last time the admin user logged into the server but I need the last time one of my network home users logged into their account. Any ideas? Thanks, Rick