What I'd suggest, as a starter, would be to get your [THN] tags all on a server at once.
There's six of you, right? Well, that's enough to make it obvious that you're a real group (you see all these clan tags and you just know there's no clan behind many of them) and yet not quite enough to totally dominate one side of the game. So you play well (and in a really friendly fashion) and people will start to ask if they can join up. Visit the same collection of servers week-on-week and you'll see the same crowds. You might even be able to get away with the occasional global chat "Visit our web site at..." message, but check the server rules on advertising before you do.
Stick together, play well and respectfully, and keep a few popular servers in your favourites list. People will start to notice that [THN] are a cool bunch of people and the ones who are looking for a group to play with will start to ask for more information. That's my take, anyhow.
By the by, what's this squad system? I don't have CoD2 so I'm not familiar with it (beyond the single-player demo).