If any of you are interested - the magic of debugfs.ocfs2 saved the day.
First task is to convert your SAN snapshot into a fully provisioned volume - that shouldn't be too hard.
Next, you need to get this disk visible to an OVM host. You don't need to view it as a repository, if you are recovering from an existing / running repository, it's most likely that you won't be able to mount this anyway.
Once the disk was visible to an OVM host - I was then able to do: