I know a few options to do that, but they rely upon software components that are missing in the current firmware (e.g. FUSE filesystem, for the developers out there) and require user interface modification, that is difficult because it is not open source. If in the future there will be an OpenBoox firmware for the M92 or another open firmware, it will be really easy to have on-the-fly decompression, but this is a big IF.
Does anybody have a better idea?