Overall, these are pretty simple. You can detect them based off of several things like the product name, probably some other stuff in the executable too. Starting at the overlay, there's some sort of header. To read it, you read 4 bytes (it's a uint32 that's a bit larger than the size of the file itself, so I'm not sure what you're supposed to use it for), followed by Windows\[name of one of the executable files inside of the actual zip] (maybe this is so the installer can create a symlink?). Regardless, you don't seem to actually need to use the header at all. Just go 1028 bytes after the start of the overlay, and there's a single embedded zip you can extract.
File used as reference: WorldwideSoccerManager2008_dd_setup_v802.exe
Overall, these are pretty simple. You can detect them based off of several things like the product name, probably some other stuff in the executable too. Starting at the overlay, there's some sort of header. To read it, you read 4 bytes (it's a uint32 that's a bit larger than the size of the file itself, so I'm not sure what you're supposed to use it for), followed by
Windows\[name of one of the executable files inside of the actual zip](maybe this is so the installer can create a symlink?). Regardless, you don't seem to actually need to use the header at all. Just go 1028 bytes after the start of the overlay, and there's a single embedded zip you can extract.File used as reference: WorldwideSoccerManager2008_dd_setup_v802.exe