If you're talking about icons you see on justin.tv's website, those are badges being displayed only on justin.tv's website. They have nothing to do with IRC. To be clear, there is no way to stream images across the server using the IRC protocol (at least not images more than ~500bytes in size, which is extremely small). If you see *any* kind of image in an IRC client, be it mIRC or justin.tv's web client, it is an image that is being displayed only on your client (and other clients that can interpret some shortcode).
And if it's not going through IRC, then it's out of scope for this forum. You should ask on justin.tv's support site / forums.
