Hello Ian,
I have followed your Mini How To for my 5.6b7 box and have it working, mostly.
I got a bit lost on the SSH Key Pair configuration, but think I have it figured out after re-reading documentation from PuTTY website. A good nights sleep can do wonders.
Thought I would give you some feedback and thank you for you work on this.
Will report back with more as I encounter it.
Steve