Hi, I made a skin for an application not written by me, which contains a modified executable with different Fonts (I know people frown upon that here, but it's done with permission from the software creator) and a folder with all the skin images.

These are the files I have:

Original executable + original folder with images
New executable + new folder with images

I'd like to install it with Inno, but I have a few problems.

1) The user has to specify the installation folder of the already installed application.
2) Check if the executable is present in that folder and if it is the correct version.
3) The user has to specify if the new skin needs to be installed or the original version.
4) Depending on the selected option, place the new executable/Image folder in the installation folder. The executable should be overwitten. The original folder with images should be removed first or else there'll be a lot of unnecessary images in the folder.

How can I do number 2, 3 and 4?
I think I need to create a custom script for this, but I couldn't find what I need in the Inno Documentation.

It should not be added to "Add / Remove Programs", because the application already has an uninstaller.

If anybody can point me in the right direction, then that would be great.