I'm afraid this particular way of getting textures is considered illegal. We cannot condone such actions on our server, which is why we will not implement a way for players to download the textures online.
The only legal way to get those textures is through buying and installing Counter-Strike: Source. I don't really see a reason to share this officially in-game with anyone, as I think the thought of having to buy a $20 game to get the "full experience" might scare some players off. If someone asks, feel free to tell them the official way of getting these textures.