How to Install iPod/iPhone Themes Without Jailbreak

Unfortunately, at the time of this writing, there is no way to install themes on iOS. There are ways, however to customize the wallpapers in themes.

You Will Need:

• An iPod touch 3rd/4th Gen or an iPhone 3GS/4 running 4.x
• Internet Access

Go To "mbtheme.com"

• This is a good site for themes, and all are packaged as .rar or .zip. One of my favorites is the "Apple Chromatic Theme" found here.
• NOTE: You will want to look for themes where, for the most part, only the wallpapers are changed, as we cannot do anymore editing past that.

Extract the files

• After extracting, you're going to want to root around and find the wallpapers and move them into a separate folder.

Move and set the wallpapers

• Easier said than done. I found the best ways were to either email them to yourself, or use one of the many download utilities with file sharing. My personal preference is Downloads by Hian Zin Jong available in a free version here or the full version, costing $1.99 here.
• You'll also want to remember which image is homescreen and which is lockscreen.

That's it!

• You should now have a themed (persay) lock and home screen. There was a way to change the app icons, but Apple blocked it in their latest iOS update. There is also a way to add battery percentage to iPod and change carrier icon on iPhone using a free backup editor called iBackupBot that allows you to change code in your backup and sync it to your iDevice. I have no expertise in those fields, so Google is your friend, and I will publish another article at a later date describing it.