Sorry friend, but unless you want to take the iPod back and find an older one (1st, 2nd, or 3rd generations), you kind of stuck, at least for the time being.
If you haven't already found it, here is the 4th genreation (mini seems to be part of this generation) page with the links to download the developer's source. Its unstable but you can supposedly get it. How to build and install it on your iPod is something you will have to research (probably a lot) on your own.
Thats all I got. Sorry.