[Jay420]

Well I've never even tried it, but you could possibly save a line in the playerfile which would be something like "Warns".
The Warns would be "0" as default, and you can create a /warn command for the admins, which will set the warns.
When an admin uses the /warn cmd, it will set the players warns:
PlayerInfo[giveplayerid][pWarns] = 1+PlayerInfo[giveplayerid][pWarns];

and

somewhere.. if(PlayerInfo[playerid][pWarns] == 3)
Ban