It's not a free download, but this sounds like exactly what you want. I've never tried this particular app, but most of the PC Mag apps I have tried have been spot on.
There are a slew of programs out there that will let you customize your explorer folder icons. But I can't find any program that will easily let me create the icon that I want. What I want is program that will let me select a folder icon and then select an icon from an exe and overlay the exe icon on the folder icon.