yes you need a mac, lots of time, and to be in the developer program. you need to completely rewrite the app exactly as it was originally written, include your picture you want in the project, get provisioning profiles and all that crap, name the app what the original app was named. and place the original app at the very last page of your home screen, and put your rewritten app where the original one was. oh you might bump into a few copyright violations on your way.