Let me direct you over to what Kodabar has to say about LAN:
"kodabar26 September 2012 at 09:29
It's already possible to play DayZ over a LAN, but it's insanely complex to do and requires installing and running an SQL database. In the online multiplayer, the servers communicate with a central database (run by Rocket) which stores your inventory and location. So to play on a LAN, it's basically the same process as running a cracked server and involves running a central database in the same manner.
This is rather tricky to get going and if you're not familiar with running database servers and routing connections, then it's not worth trying. There are instructions out there on various sites explaining how it's done. None of the ones I've seen are particularly well-written or clear, but you can find them if you try.
Hopefully it might be possible in the future to run LAN play in a simple manner without having to run a database at the same time. Maybe Unknown will try that, but it's not likely that it's imminent. Note: I haven't actually discussed this with him, so I don't know his plans in this area, if indeed he has any."
In other words, it's extremely difficult to do, even if you have some basic knowledge about computers, networking, etc.