This is an issue for both WEP and WPA/WPA2 and it caused me significant frustration to the point where I put the board in my drawer for a month and didn't touch it. However, I found a workaround yesterday and got it working by using the instructions on this page, but with one important modification:
Connecting to a Wireless Network via Linux*
Where it says:
> set_network 0 psk "Your Network Password"
Do not use the quotation marks. Instead, type in your hex digits without quotes:
> set_network 0 psk HEX_DIGITS
I have not tried this, but it looks like one might be able to modify the /usr/bin/configure_edison script to change this, perhaps removing the quotes in the WPA templates. If you try this and have success, please post the solution. It would be useful if Intel provided an official solution for pre-shared hex keys.