The problem:
I'm using a MacBook, mainly with Solaris 11, but something with Mac OS X (ML). The only missing thing is that Mac OS X can't read my external ZFS based USB drive, where I store all my data. So, I decided to look for a solution.
Possible solution:
I decided to use VirtualBox with a Solaris 11 VM as a passthrough to my data. Here are the required steps:
Installing a Solaris 11 VM
Install VirtualBox on your Mac OS X, add the extension pack (needed for USB)
Plug your ZFS based USB drive on your Mac, ignore it when asked to initialize it.
Create a VM for Solaris (bridged network), and before installing it, create a USB filter (in the settings of your Vbox VM, go to Ports, then USB, then add a new USB filter from the attached device "grey usb-connector logo with green plus sign")
Install a Solaris 11 VM, boot it, and install the Guest addition
check with "ifconfg -a" the IP address of your Solaris VM
Creating a path to your ZFS USB drive
In MacOS X, use the "Disk Utility" to unmount the USB attached drive, and unplug the USB device.
Switch back to VirtualBox, select the top of the window where your Solaris 11 is running
plug your ZFS USB drive, select "ignore" if Mac OS invite you to initialize the disk
In the VirtualBox VM menu, go to "Devices" then "USB Devices" and select from the dropping menu your "USB device"
Connection your Solaris VM to the USB drive
Inside Solaris, you might now check that your device is accessible by using the "format" cli command
If not, repeat previous steps
Now, with root privilege, force a zpool import -f myusbdevicepoolname because this pool was created on another system
check that you see your new pool with "zpool status"
share your pool with NFS: share -F NFS /myusbdevicepoolname
Accessing the USB ZFS drive from Mac OS X
This is the easiest step: access an NFS share from mac OS
Create a "ZFSdrive" folder on your MacOS desktop
from a terminal under mac OS: mount -t nfs IPadressofMySoalrisVM:/myusbdevicepoolname /Users/yourusername/Desktop/ZFSdrive
et voila ! you might access your data, on a ZFS USB drive, directly from your Mountain Lion Desktop. You might play with the share rights in order to alter any read/write rights as needed. You might activate compression, encryption inside the Solaris 11 VM ...