Game Center without Unity Pro

Is it possible to integrate GameCenter or other iOS kits to iPhone games on unity without having Unity Pro? For example, a way to implement it without a plugin?

UPDATE: After a while i found out plugins do work if on the basic iOS license in Unity

It is possible to use GameCenter without Unity Pro. Check out this.

( This is a working script )
http://forum.unity3d.com/threads/104747-Unity3d-GameCenter-Leaderboard-Tutorial