over the last days I have programmed a little partimage extension providing support for "unknown" file systems.
My approach is that partimage could treat those file systems like 100% full filesystems and simply save each and every block of it.
The changes to the source code are quite overseeable, I think.
The modified partimage basically ends up in a dd-like operation. I've tested it with some exotic partitions and it seems to work - it still needs further testing though. If you fill the unused areas of the file system with zeros, compression still seems OK. However, speed is an issue compared to supported filesystems.
I would be happy to provide a patch against 0.6.4 for consideration by the core developers. Where can I send it ?