The yellow things mate with these flats much like a spanner so when the studding turns, they turn, the holes in the other end will have push rods (radio control car track control rods), two each, that will open the throttles. Using the track control rods means the action of each throttle will be individually adjustable.
At the back of the picture is a bracket which will bolt in place of the existing linkage bracket. The big hole will have a ball bearing for the studding to run in, a couple of pulleys, the mounting points for the twin cables & open & closed throttle stops & a return spring.
This is still all at an early stage of development, but it looks like it should work.