How can I install iOS 7 on my iPod touch 4th gen?

You can't

The iPod 4th Gen does not have enough RAM for iOS 7

So iOS 7 is not able to be installed

Allan

You can't

. As Apple said in June, iOS 7 is not compatible with the 4G iPod.

All the iOS devices compatible (iPhone 4 and later, iPad 2 and later, and 5G iPod touch) with iOS 7 have at least 512 MB of memory (RAM). The 4G iPod only has 256 MB