Probably about the best your going to do with KiXtart is to write a log file every logon which has the date and current IP and MAC address. Since KiXtart only runs when a user logs in, it is not a live dynamic solution.

Since machines can renew their IP address inbetween logons, there is no "live" way for KiXtart to get that information for you.

You might be able to query/read the Microsft database that stores this information, but then again you might corrupt it trying to read it in a live situation using remote methods.