For macOS Sierra (10.12) and OS X El Capitan (10.11), you also need to boot into the Recovery OS (either the Recovery partition or bootable OS X install media for 10.11) and run
csrutil enable --without kext
The latter will allow you to load your custom-built, unsigned kernel extensions, while keeping the rest of System Integrity Protection (SIP) in place. (Depending on your needs, other options you may want are --without fs, --without debug, --without dtrace, or --without nvram. If you specify all of them, that is equivalent to csrutil disable. The --without option takes a comma-delimited list or can be specified multiple times: --without kext,debug,dtrace is equivalent to --without kext --without debug --without dtrace).
If you have any other implementation of ZFS installed, you must uninstall it and reboot before proceeding further. Similarly, if you have installed the O3X installer version, please follow the uninstallation directions before proceeding.