Currently Being ModeratedFeb 17, 2013 8:53 AM (in response to Josef_M)
Your only way is if you have the version that was compatible on your computer such as in the recycle bin/trash or in a computer file backup. In that case delete the current version that is in your iTunes App library and replace it with the older version. Then sync.
Apps are locked to the account that purchased them. Thus, you would have to sign in to the account that purchased the app to install it on your iPod.