Install FreeBSD with root-on-ZFS.

1. Burn the memstick image.
   dd if=/path/to/FreeBSD-10.0-RELEASE-amd64-memstick.img of=/dev/da0 bs=64k
2. Mount the newly created image.
   mount /dev/da0 /mnt
3. Copy the script to the image. (Yes, there is space.)
   cp path/to/zfsinst /mnt/bin/
4. Unmount.
5. Boot the memstick image.
6. Select LiveCD.
7. Log in as "root".
8. Run zfsinst, answer the questions.

• Integrate into bsdinstall scripts, or possibly
• Provide a patch that modifies an existing memstick.img filesystem to provide zfsinst as an install option at the Welcome dialog in another dialog after <Install> is selected
• Provide instructions for building an original memstick image (n.b. man release and make memstick)
• Add overrides for filesystem layout (we currently assume layout based on number of raw devices)
• Add option to customize name of zpool
• Built interactivity into standard dialogs
• Test in FreeBSD 11, modify as required

• https://wiki.freebsd.org/RootOnZFS