Make a folder somewhere on your computer named "artwork". Inside that folder create another folder named "pngs". Download iphoneshop-0.72, should find it here....
Link
After you download the file place it in your "artwork" folder as well
Ok, now browse to your "System/Library/Frameworks/UIKit.framework" folder on your phone using whatever program you get into the iPhone from your computer. Save the other.artwork file in your artwork folder.
I use a Windows PC, so this is where it may start differing from you if you use Apple.
Click on "start", "Run" and type "cmd". Hit OK. This should bring up the black command prompt screen.
In command prompt type "cd (then the listing where your artwork folder is located)" without the ""
(For example mine would be cd C

Users\Doomi\Desktop\iPhonestuff\artwork)
and press enter. The directory listing on Command Prompt should change to your artwork folder.
Now copy and paste the following line into your command prompt screen
java -jar iPhoneShop-0.72.jar ARTWORK Other.artwork export pngs
Your command prompt should now scroll through a bunch of lines, and when it stops you should now have a bunch of .png files in your "pngs" folder.
When you have edited the files to your liking, save them and make sure they are all still located in your pngs file with everything else. Now, back in your command prompt, make sure your still pointing at the artwork file, and copy and paste this in and press enter:
java -jar iPhoneShop-0.72.jar ARTWORK Other.artwork import pngs
Your command prompt should do a lot of scrolling again, and when it is finished you should have a new Other.artwork file located in your "pngs" folder. Replace the same file on your iPhone with this new one and you should be good to go.
If you are on a Mac you might want to take a look at this link as the steps are the same, just the command prompt is different.
Mac
Hopefully this works for you.