Yep, I've got some scripts that I've successfully run chrooted. Backup is quite straightforward:

Naturally, replace zlib with lzo for that option and /tmp/mnt/rootfs to wherever the rootfs partition is mounted. Then ubinize that image:

The zlib here is of course optional, I just use it to distinguish between zlibbed and lzo'd images. BackupMenu would need to add the date stamp too, but as these are just my testing, I didn't bother; the ubinize.cfg is the standard one posted previously, with /home/user/MyDocs/systemBackups/rootfs.ubi.img in the image parameter. This can stay without any date/time as it's only a temporary image anyway.

Then for restore:

This assumes that the rootfs partition is at mtd5, I can't imagine it would ever be anywhere else, but perhaps some sanity check to be completely sure. Again the rootfs.zlib.img would need a date/time for BackupMenu. I also think doing a ubidetach prior to flash_eraseall and nandwrite, then ubiattach afterwards, would be safer; the rootfs partition should be umounted too:

Neither ubiattach/detach need new libraries, just the standard libc and linux.

Hope this helps