You're best bet would be to contact Jason Buckle directly. That song's never been released commercially, and when it appeared on Buckle's myspace page, it was the first any of us had ever heard of it.
It's possible somebody digitally recorded it directly off of Buckle's myspace page, but I imagine the quality will be less than desirable.
But if you are brave enough to confront the source, why stop at Dirty Dick. I suspect Jason is sitting on dozens of recordings of never-before-heard RM tracks.
