First thing before you want to customize your phone or iPod without Apple control, you need to Jailbreak it. There’re many way to jailbreak your iDevice, but it’s not the main point here.
In second step, you’ll need Winterboard. Winterboard is an application that let you customize your iPhone/iPod. Winterboard allows you to customize Springboard of your iDevice. Using Winterboard you can change its icons, customize applications, status bar graphics, dock graphics, install themes and change wallpapers of your iPhone/iPod Springboard. You can even customize sounds on your iPhone. With Winterboard you can theme almost everything that comes to your mind. And now I will guide you with the installation.
Perquisite: how to install Winterboard on your device.
1.Launch Cydia from SpringBoard
2.Tap the Search tab located on the bottom tab bar and search for WinterBoard
3.Once WinterBoard appears, tap it. Then tap Install.
4. Then you should now see the WinterBoard being installed. Once installation is done, tap Reboot Device and wait for your iDevice to return to the lockscreen
Now you get Winterboard on your device and can start freely customize your device. You can do it by downloading your theme from Cydia or by the way that I prefer, downloading from sites and copy it to private/var/stash/Theme.xxx throught iFunbox. It’s common for theme, lockscreen, status bar… You just need to go to Winterboard, tick on Winterboard’s configurable options, respring and … boom … your iDevice now looks so fantastic.
In all part that Winterboard can change, I like to play on Lockscreen because it change your iPhone/iPod excellently in a so simple way.
All over these complicate steps I told you, the most important and hardest steps is how you can get the right Locksreen for Winterboard. Not all Lockscreen in Cydia n sites is at your kind. Ewww, it’s really difficult, right? But now, it’s the easiest and simplest stage, because I will bring you the most simply beautiful Lockscreen right now 
Top 15 Lockscreen for iPhone 4/ iPod touch 4th of Shurigen
1. Rice Wine HD
LS Rice Wine HD for iPhone 4 is a simple but elegant approach towards a LockScreen theme. All the information is displayed on the top part of the screen, you get the normals Day, Date, Time & month displayed plus the Weather & the year
2. Danael M9
Danaël M9 Lockscreen is a brand new twist on the Lockscreen by Danaël a French native. The theme features a very clean pop up with date and time.