How to customize iPhone 4 app icons?

I've tried cocoppa, app icons, and a few others. But what you actually download is just an extra shortcut, not a replacement icon - so you'll end up with two icons on your home screen for the same app, with an annoying blank page open for a few seconds before opening the program. My question, is there an app, or way to replace the original app? Hope my question makes sense, sorry for rambling, and thanks for an answers!

Unless you are the developer of the app you will not be able to change the original icon.

No. Apple only allows "soft" OS customization (for reliability, security).

You can hide the original icons in a folder and move the folder to the last page.