Just noticed this. Hopefully you already figured it out, but in case you or anyone else needs a hand:
I'm going to guess that you're trying to connect the printer to the SBG6580 via a wireless connection.
With that in mind, the WEP key or password is usually set by your ISP if they're managing the modem (if not, you can log into the modem by opening your browser and going to »192.168.0.1 or »192.168.1.1 in most cases, and setting the wireless SSID and encryption password.
WPA2 is preferable over the less secure WEP). If you don't have your wireless password handy, call your ISP and have them give it to you or reset it if needed.
Then when the printer asks for the password in hex or alpha, you should select hex if the password is only the numbers 0-9 and letters A-F, or alpha if you are using 0-9 and letters A-Z and/or symbols and spaces in the password).
Hex stands for hexadecimal and is a type of numbering used by computers, and uses the letters A-F to represent the numbers 10-15.
Alpha is for alphanumeric (numbers and letters)
Hope this helps!