As just a straight-forward, click here, type this, click here... no, not at all - that sort of stuff is encrypted to protect someone else from stealing that information from you. I'm a comp. tech. guy that loves to hack and figure things out, but even with an extensive background in programming, hardware, hacking, and work-arounds, I would be intimidated by the thought of tampering with a $300 product. Basically what you're talking about would require you to tap into the root of the iPod through a modified attachment (likely a usb cable, cut and linked with a customized hacking firmware), locate the specific location where the information is stored in raw format, then decrypt that information... I know I say that like its a weekend fix, but we're talking several months of trial and error, revamping, and starting over... Unless some rogue iPod Engineer has released some critical code (I don't know, I don't care), it would be WAY too much work just to get a wireless key. A more likely possibility is if there is an iPod app already out there that is built to decrypt password keys. (There are some for Windows, but that won't help here.) A much easier solution would be for you to have access to the router you are trying to get internet access on, and just change the WEP key to something you can remember.
If this is the case, reply back and I will post information about how to find your router's IP address from your computer, connect to it, and a general tutorial on how to change the password. If you do reply, make sure to let me know what operating system you're using.