Taken from Wikipedia:
Proprietary authentication
One criticism
[by whom?] of the Wi-Fi USB Connector is that it uses a proprietary authentication mechanism. Because of this, the Wi-Fi USB Connector works only with approved devices, which at this time is limited to the DS and Wii consoles.
[5] This behavior was an intentional design decision on the part of Nintendo, as it prevents outside parties from connecting to the Wi-Fi USB Connector with their computers and accessing the user's Internet connection or computer.
While the Wi-Fi USB Connector can be modified to circumvent this,
[3] the modification is beyond the capability of most users and is naturally unsupported by Nintendo.
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However after skimping through another Google, I found this. http://www.digifail.com/text/wfchack.shtml
It is a tutorial to hacking your Nintendo Wi-Fi USB Connecter, I have not read or used it, but it was the first one to pop-up. (I Skimmed right through it).
If any problems or issues come you will know where to go.