Do you mean, get the WEP passphrase from your router and apply it to the PS3 ?
Link computer to router using ethernet cable, log in to router setup screens via your browser (for router IP address and login Username and Password see router instructions or download the maker's manual). If the setup login password has been changed you'll need to reset the router using the reset button (usually below a pinhole).
Once in go to wireless settings, wireless security and have a look at the passphrase -- if it's ****out you may have to set a new passphrase.
If it's in hex code, Right click on it and copy. Later paste in to PS3's security user interface (I'm guessing here because I not familiar with the the PS3).
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