To stop the bike shifting around too much, make sure it is in gear, stops back wheel turning.
Also: Tie a bit of string, bandana, whatever, over throttle binding the front brake.
Now it wont roll backwards or forwards. 
Bind the front brake
... Now why didn't I think about that...?
I think it was in gear - it was when I left the seat 
In mud. Slippery as hell. Check my vellies.
Not realy bum on the seat but more or less the technique shown in the threads.
Locked handle bars. In gear, left hand locking front brake, right hand on rail. Lifted it very quickly. (Maybe some adrenaline helped). Bent knees, straight back. Should be a piece of pie in sand.
Given. If the fall was to the other side, the locking of the front will not be an option. (I think). Maybe then Jaq suggestion.
I have a bad lower back. This method works the best for me, although I have picked up the bike with the front method as well. Just as quickly. Adrenaline is an amazing thing. Do it quickly and adrenaline is still there to assist. Wait a few and have a smoke/break before picking it up, and it's much more difficult. (In my experience so far)
I'm just very aware of possible back spasms doing it with a even slightly bent back.

