[Seven.]

Hope this helps you

pawn Код:

// Somewhere in your commands script: (edit to your own code :) )

dcmd_saytoirc(playerid,params[])
{
    new msg[128];
    new message[128];
    new name[MAX_PLAYER_NAME];

    GetPlayerName(playerid, name, sizeof(name));

    if(sscanf(params, "s", message)) return SendClientMessage(playerid,color, "Usage: /saytoirc message");

    format(msg, sizeof(msg), "%s(%d) has said: %s.",name,playerid, message);
    CallRemoteFunction("igmessage","s",msg);

    SendClientMessage(playerid,color,"You have send the message to irc channel!");

    return true;
}

// Put this in your irc script!

forward igmessage(const string[]);
public igmessage(const string[])
{
    IRC_GroupSay(gGroupID, IRC_CHANNEL, string);
    return 1;
}

EDIT: For your 2nd question, about when someone joins a irc channel. You will be needing to create a IRC bot that will send the message ingame with !m Person: X has joined our irc channel!