I take it you have tried the iwconfig GUI in the DSL menu under "Setup>Net Setup" and changed "device" from "eth0" to "ath0" before entering your network details. In that case, what error message did you get?
Many Atheros chipset devices are supported by drivers included in DSL, but if your one isn't detected, you may have to track down and configure another driver.
Error message from net setup>iwconfig = "connection failed"
Error message from control panel>wlanconfig= "no wireless network card found"
device ath0 (also tray eth0)
sid wlan-ap (name of my router)
wep ******* (wep password)