I have one sitting in one of my spares boxes I take to races. I have not fitted it, but you use the short cable directly in to your gear box and it sits up above it. Obviously you need to then route the excess length of your original cable so that it isn't a problem.
It is correct that if fitted to lighten the clutch it will reduce lift, it has a three ratios, depending on where you put the pivot pin, which would need to be trial and error for your needs. I had intended to use it mounted 'backwards' to actually increase lift, lever pull force not being my particular problem. If you did that the pull would of course be heavier.
In the end I bought a very expensive Domino lever with an increased fulcrum length (33mm) that gave me more lift. It is still marginal, last time I raced the bike the clutch centre nut came slightly loose and I had clutch drag waiting on the line for my second race start!