How do I make it say CONSOLE: (what you want it to say) in my server chat.

[Ocelotus]

Two other questions, related to the subject:
How do you make a join message,
or a leave message, and either one using console commands?

Are you trying to fake join and leave messages?

[Ad Bot]

[NumberOneTuxedo]

Are you trying to fake join and leave messages?

Yeah.

[$trinick]

Why would they ever not function though?

Never assume that anything is going to function as intended when developing anything.

[Johnny Blockhead]

You could just announce it in blue text, like so:
announce("\c1Piexes has left the game.");
I'm not exactly sure if that's the correct blue though. You could use something like hex codes, maybe a search would find the exact color.
In order to make it a bit fancier, you could also create a server command that takes in a name, and then says that they've left the game.

[Zeblote]

The join message would be:

messageAll('MsgClientJoin', '\c1%1 connected.', "player name");

The leave message is more complicated if you also need the sound that goes with it, as this is normally handled in a secure command which you can't call.
First, create a sound datablock:

datablock AudioProfile(LeaveSound)
{
    filename = "base/data/sound/playerLeave.wav";
    description = Audio2D;
    preload = true;
};
TransmitDatablocks();

Then to send the message and play the sound:

messageAll('', '\c1%1 has left the game.', "player name");
ServerPlay2D(LeaveSound);

I think it would work, but you'll have to test it.

[$trinick]

I believe the tag is 'MsgClientDrop' to send via messageAll to play the player leave sound.

messageAll('MsgClientDrop', '\c1%1 connected.', "player name");

Nope. That tag is gone now. Dunno why.