This machine uses the:
Apple 630-2883 Original APPLE-MAC Airport 802.11B Wireless Card from the 700 MHz machine through the eMac (ATI Graphics). After that it uses the Apple M8881LL/A AirPort Extreme Card.
Installation of the AirPort Card on this machine is very easy.
Press the eject arrow located on the upper right corner of your keyboard. Once the optical drive tray is open, gently hold it and shut down the machine.
Remove the two Phillips screws located to the right and left sides of the optical drive tray.
Gently remove the panel from the front of the eMac
Disconnect the AirPort cable from the optical drive panel.
Pull the AirPort card straight away from its socket in the eMac.
Slide the new AirPort card into the slot until its firmly seated.
Reconnect the AirPort cable to the optical drive panel.
Reattach the optical drive panel and restart the eMac.