How to set up ZEVO / ZFS on an internal disk while maintaining full disk encryption?
Short answer … two Core Storage logical volumes, both encrypted: 


one LV, HFS Plus
the other LV, give to ZEVO. 


You'll need ZEVO Community Edition 1.1.1 (1.1 is outdated). 

In the answer to the linked question there's a note about Mountain Lion; OS X 10.8.5 makes things a little more difficult.