New Way of Joining a Public Usergroup

[evenmonkeys]

My forum is basically for a clan from a video game that I play. However, I've also made it into an informational site so it attracts a lot more than just my clan members. This being said, I was wondering if the following would be possible.

When you sign in on the game, you get a clan message. What I want to be able to do, is put a "security number" or a "password" in the message that the people in my clan would be able to enter into an area; thus granting them access to the usergroup. As of now, you have to go into group memberships and apply to have access... then await for me to handle it. What I was hoping was that someone could create a hack that would allow a user to type in a number... and if the number was correctly entered, they would be given a secondary certain usergroup instantly.

I'm sure it's not as easy as I think it would be, but I still hope someone can do this.