Access code for online play? If you mean the WEP key, you have to find the owner or maintainer of the Wi-Fi connection and get the key from them.
As far as that being said, I don't have the slightest rememberance of any code, unless your Wi-Fi has a password on it. And I think that applied only to the browser.
Can you get us some more details? And someone should move this into the appropriate sections.
And welcome to PSPMod.com. Read the rules and observe respect for everyone else.