I was able to use the ZFS install menu in FreeBSD10-BETA3 without problems. I am having some issue with -BETA4:
http://solitaire.jruehlig.com/owncloud/public.php?service=files&t=ec0291fb9e76d42c3340ae805991ac88
http://solitaire.jruehlig.com/owncloud/public.php?service=files&t=ec0291fb9e76d42c3340ae805991ac88