binaries of mtd-utils are inside bootmenu flasher
http://fanoush.wz.cz/maemo/initfs_flasher.tgz
For flashable backup you just mount jffs2 system somewhere and create jffs2 image out of it via mkfs.jffs2. Example for rootfs
Code:
mount -t jffs2 /dev/mtdblock4 /opt
mkfs.jffs2 -r /opt -o /media/mmc1/rootfs.jffs2 -e 128 -l -n
later you can flash it (when booted from something else than internal flash) via
Code:
flash_eraseall -j /dev/mtd4
nandwrite -a -p /dev/mtd4 /media/mmc1/rootfs.jffs2