mount zpool from a zfs volume

[Robert Wing]

I want to import a zpool from a freebsd-zfs partition that is backed by a
zfs volume. Is this possible? The sequence of commands that result in
success are eluding me.

gpart show:
    =>      40  33554352  zvol/zroot/vol  GPT  (16G)
               40      1024               1  freebsd-boot  (512K)
           1064       984                  - free -  (492K)
           2048   2097152               2  freebsd-swap  (1.0G)
     2099200  31453184               3  freebsd-zfs  (15G)
   33552384      2008                  - free -  (1.0M)

zfs list (relevant parts):
    ... zroot datasets ...
    zroot/vol           16.5G   367G   672M  -

I've tried 'zpool import' which produces no results, also tried explicitly
with the -d option. The results of this command lead me to believe that the
pool from the zfs volume is not being exported.

I tried using 'zfs mount zroot/vol', failed with: operation not applicable
to datasets of this type.

The zfs volume is the backer for a VM, this is what I'm trying to acheive:
     1) shutdown the VM
     2) import zpool from the VM
     3) make changes to the VM zfs datasets
     4) export the zpool
     5) re-boot the VM.

Anyone point me in the direction of enlightenment?

-Rob