This is getting a little cumbersome and confusing.
My /etc/wpa_supplicant/wpa_supplicant.conf file looks like this:
ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=0
update_config=1
ap_scan=1
network={
ssid="MY SSID"
key_mgmt=NONE
group=WEP104 WEP40
wep_key0="aaaaaaaaaa"
}
So I changed wep_key0 to the hex of my key which is "33643039323434356239" but now when I reboot the Edison the WPA Supplicant Service fails to start.