Hi, I'm the guy who made the original topic/guide. Got a tip from someone that this thread existed and I thought I'd stop by.
Basically, all you need to do is change the DNS in the DS wifi settings to either 126.96.36.199 or 188.8.131.52. The annoying thing is that as you may know, the DS doesn't support most modern networks. I have 5 different ways of getting around this, and some of them work for different people.
1. Tether an older router to your main router and connect your DS to it
2. Make an open hotspot on an Android Phone
3. Use the Nintendo Wifi USB connector with a virtual machine
4. Set your main network to open or create an open guest network
5. Go around to various public places until you find an open network with no login page
I already went into more detail about this in the thread at Gamefaqs, but if you guys have questions or want more detail here then I can help out. Either way, it always makes me glad to see interest in this game.