Just a matter of physically getting a textfile containing your WPA2 PW string onto the Ipod. I've got very long, very cryptic WPA2 passwords on my wireless network, complex enough you'd never want to even try typing them in.
Save the PW string to a text file on the PC, install which ever text reader/editor app you prefer onto the Ipod touch. I use Goodreader, but there's lots to choose from.
Plug the Ipod touch into the PC, go to apps tab once the app is installed on the Ipod, add the text file you created on the PC containing the WPA2 PW to the app. Fire up the app on the iPod, then copy and paste it into the WPA2 password tab on the iPod once you switch back to the wifi setup section.
Or you could simply email the PW string from a PC email client to the iPod if you have an open network you can hop on for a second on the iPod. Then select all, copy and paste to wifi setup section. Same method, just a different delivery.
I do this with my Ipod Touch, iPhone, iPad and new Galaxy S3 and it works a treat. Android device is a little easier cause I can simply diskmode it. The Apple devices require a little more work due to the "walled garden" approach.
EDIT: regarding copy and paste on the ipod, it occurred to me you may simply not know how to do it. If that's the case, see the below link. If that's not the case, my apologies for treating you like a child
Works pretty much the same for iOS 3 and up.
http://answers.yahoo.com/question/index?qid=20090618131240AAq2yrN
