Wrench
With just naming the folders to match those of a stand along install, and if you included everything a person needs, it should be a drag and drop affair. Not sure why a "nightmare" readme will be needed.
Example:
Unzip the package, to a folder on your desktop.
Make sure after you have unzipped the folder, to check it to make sure a folder hasn't nested in another folder. If it has then that folder inside the unzipped folder is the one you will need to drag and drop into your install area which looks something like:
C:\Users\username\Saved Games\ThirdWire\IndoPak (using IndoPak as the name of a stand alone install)
Then do the following...
Drag the Sounds folder to the C:\Users\username\Saved Games\ThirdWire\IndoPak
Drag the Objects folder to the C:\Users\username\Saved Games\ThirdWire\IndoPak
If you keep it that way then it will keep the "nightmare" readme out of the equation. Try to include everything that this mod needs so no one has to hunt for it.