Massively impressed by the bespoke game controller above from Remap's Leicestershire and Rutland panel. This is an approach I've not seen before, but it looks like it works brilliantly.
The need for this type of controller I have seen before. Other solutions for people include that of Marc Busnel in France and by using an array of Altec Ultralight switches.
Update 06-01-2014: This controller was built by Graham Law which interfaces into a standard console switch interface.