So, I downloaded Virtual Router and MACpass...
I set up the IP and the DNS settings as described in
DarkKnight's guide, and made sure the SSID was set to "attwifi"
This gave me the "Nintendo Zone is available" prompt, and my 3DS keeps popping up and disappearing in the Virtual Router window (I'm guessing it checks for streetpasses quickly and then disconnects, instead of keeping a consistent connection to the hotspot.)
I've successfully been changing my mac addresses using MACpass. It'll change the MAC address for my usb wifi adapter (Named "Wi-Fi"), as well as the virtual network (named "attwifi") at the same time, just like it should.
This has allowed me to get streetpasses successfully ONCE after cycling through about 50 different MAC addresses.
That seems kind of high... so I thought there might be a problem. Then I noticed something:
The MAC Addresses that are listed are ever so slightly different from each other. "attwifi" always has one character that is different from "Wi-Fi"
For example: If MACpass is attempting to change the MAC to "4E-53-50-4F-4F-4
E", then
"Wi-Fi" will show it correctly, as "4E-53-50-4F-4F-4
E", However,
"attwifi" instead, shows it as ""4E-53-50-4F-4F-4
F"
It's always the last character that ends up getting changed, and I have to wonder if that means I only successfully access a correct MAC address sometimes, while the rest of the time, it's just cycling to random, useless MACs, and I'm sitting there twiddling my thumbs.
If anybody has any insight into this, it would be much appreciated.