Default [Q] Edify: Access file of update.zip directly using busybox?

Hi

How can I access files of my update.zip directly using busybox? In general, I'd extract all the files by the operation package_extract_dir("system", "/system") to have access to the extracted files. Now I'd like to avoid this step to unzip a file on my update.zip directly, whithout copying to the system partition, but I don't know how to access this temporarly loaded file using busybox? I do my updates by sideload.

Any ideas, someone already tried this?
Regards