You can use the CLI utility 'gpart', it's very intuitive IMHO. E.g.
[shows your partitions on all disks]
[even more detailed]
gpart add -t freebsd-zfs -a128k ada0
[adds a FreeBSD-ZFS partition with 128k alignment to your 1st HD]
Since you're an experienced Linux user you will be happy with it and maybe start writing a GUI for it.
For information on ZFS, do not crowl the net with "FreeBSD ZFS", your search engine will show too many results that distract you. Better 1st play around changing the default settings and ask again once you have problems