You can't unless you have one specific wireless card.
Someone made a driver that will interface one specific wireless chipset with the DS (and the chipset is not made anymore)
So basically you have 3 options
1. Find a network board with the right chipset and get the driver from the net
2. Buy the usb dongle that Big N makes just for that purpose.
3. Write a driver for your own wireless card to get it to work.
http://www.aaronrogers.com/nintendods/wifime.phpA link to a page that tells you about the one wireless board that will work and the driver.
http://en.wikipedia.org/wiki/Nintendo_W ... _ConnectorIs your best bet. I have seen them in the stores but they are getting rarer. Pretty sure you could get one off the net still.