You may or may not know that because of an inner tubing accident January of 1982, I am paralyzed from the waist down. So I am not that good with a foot clutch. :) I spent over 2 1/2 years restoring this Amphicar (95% alone) and only after I finished it did I start on making the hand controls. About 25 people got to drive my car before I did. Backwards, yes, but effective incentive to make it work. 

    I did much the same thing with the hand controls I built and patented (5.299.652) for my Harley. However they were very different because the Harley already had a hand clutch and I needed to operate the foot shifter by hand. The Amphicar already has a hand shift and I needed to operate the foot clutch by hand. With both, one feature was a non-negotiable. This being that all factory controls must operate and appear as stock but without interfering with the hand controls or visa-versa. No permanent modifications with the exception of a single hole to pass the clutch cable through, were made. The following short pictorial (mouse over each picture for more info) illustrates how I accomplished the task at hand, umm so to speak! :)

Hand Operated Vacuum Assisted Hydraulic Clutch:

The view under the dashboard showing the controls mounted beneath.

The view of inside the trunk showing the master/booster and temporary mountings.

The view of the clutch arm showing slave cylinder mounting.