A modified unsquashfs utility that attempts to support as many hacked-up vendor-specific SquashFS implementations as possible.
If the vendor has done something simple like just muck a bit with the header fields, this tool should sort it out.
If the vendor has made changes to the underlying LZMA compression options, or if/how this data is stored in the compressed data blocks, this tool can try to detect these customizations via a brute-force method.
Very beta.
You need a C/C++ compiler, plus the liblzma and zlib libraries (if installing from a package repo, install the development packages).