Good Job Mate
when you are using external compressors it becomes difficult to track decompression, so maybe an archive(Setup0.bin?) with all decomp exe(resources needed for decompression)
can be created
so that setup.exe can extract it before everything (in {tmp}) and walla we don't have to change every single script for a new compression
also, we can know it's size beforehand so you can set disk span value accordingly