Kinell! It was 6 years ago I dun it.
Still working a treat - unlike the rest of the Landy!
http://www.landyzone.co.uk/lz/f38/upgrading-defender-windscreen-washers-67811.html
Yes, diff lock on, gentle right foot, highest gear possible but avoiding stalling or clutch slipping.
I find low 2nd on tickover very effective for that sort of thing.