Well, I expect the button to do a dns lookup after joining the network… you could track this with a tcpdump (wireshark may help). After that, maybe the button will do a kind of HTTP request ?
If the button does this, you could : force the DNS to “localhost” and set-up a small web server to catch the request… :)
Will check if I can order such a button here in Quebec… :)
Good hack anyway !