[Vince]

pawn Код:

public OnPlayerConnect(playerid)
{
    if(playerid == GetMaxPlayers() - 1 && !IsPlayerNPC(playerid))
    {
        SendClientMessage(playerid, COLOR_RED, "We're sorry, this slot is reserved.");
        Kick(playerid);
    }
    return 1;
}

That's as close as you can get.