This is an advanced how to involving a manual installation from a live CD environment, utilizing some advanced techniques such as partitioning from the command line with advanced tools, and compiling the operating system from source code. The goal of the document is to allow someone unfamiliar with the process to follow the document and perform the tasks. However it should not be attempted by someone who is unfamiliar with FreeBSD in General. This document was based on proof of concept testing, I have done all the steps and verified them to work in test environment, prior to writing this documentation. Then I used this documentation to convert all my production FreeBSD servers to ZFS, which I have been running since version 9.2, the current instructions are tested on 10.1, I believe they will still work with 10.0, but some steps have changed that will not allow them to work with 9.x versions.
I take no responsibility for the overall outcome of the procedure outlined here, if you chose to proceed and follow these steps for yourself, you do so at your own risk.
Also its important to note that this process is no longer required as of the FreeBSD 10.0-RELEASE, since it includes a ZFS installation option. However, I still use this procedure on any installs I do, because I prefer to make some customizations on how the ZFS Dataset are created.