You need to use an SFTP thing-a-ma-bobber (that's the scientific term, thinga majiguris). Depending on what system you use-- Apple or Windows-- you would use __(insert Apple one here, something to do with Quacking or a Duck?)__ or WinSCP. Open up the client (after jailbreaking) and put in your iPod's IP Address (you must be on a Wi-Fi network) that you can find by hitting the blue arrow on your iPod's Wi-Fi Settings. Once that's in, type in "root" for user and "alpine" for password. There should be a bunch of folders on your left (your computer) and a bunch on the right (your iPod). click the up arrow or ellipsis (...) on your iPod's side a few times to make sure you are on the homepage, then click on the names you just said for the directory. Find the folder in your computer (the left side) where you have the files, and drag and drop them to copy them onto your iPod.
I'm sorry for the wall of text, I truly am.